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HIGH-FIDELITY OUTPUT CIRCUITS 




Electronic Control 

for Your 
v Ventilating Fan 



Servicing Home 
Tape Recorders 



Field Experiences 
in 

Color TV Service 



Troubleshooting 
AGC Circuits 



VCX/g REP£/rA7/Ofi/ it, //W e*s/o/> / 




/IS 

cuo/ee 



It's more than just a picture tube- 
it's performance, dependability and a 
guarantee. And your reputation 
is riding with it. 

Your customers take your word for the 
quality of the picture tube you install. 
It's easy to assure top performance, long 
dependable life and a guarantee that 
means something by recommending and 
installing Du Mont Twin-Screen Hi-Lite* 
picture tubes. Du Mont has been manu- 
facturing cathode-ray tubes for 25 years. 
All of the experience in engineering, 
design, and technical skills compiled 
in these 25 years years go into the 
Twin-Screen Hi-Lite * 

The picture tube is your choice-and your 
reputation. Back that reputation with a 
reliable Du Mont picture tube. 

*The ultimate in aluminized picture tubes. 



Cathode-Ray Tube Division ALLEN B. DU MONT LABORATORIES, INC., Clifton N. J 




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I WILL TRAIN YOU AT HOME 
|) FOR GOOD PAY JOBS IN 

, RADIO-TELEVISION 

J. {. SMITH has trained more men lor Radio-Tel^vtsion ^^4M P^^i I J fts^^fll^Hk 

>v than any other man OUR 40th YEAR ^^fl P^J^Ll^PP^^^^B - ^BB 



America's Fast Growing Industry Offers 
You Good Pay -Bright Future -Security 



I TRAINED 
THESE MEN 



"Started to repair sets six 
jj*^^^ months after enrolling 



Earned $12 to $15 a week 
in spare time." — Adam 
Kramlik, Jr., Sunneytown, 
(Pennsylvania. 



"Up to otar necks in Radio- 
Television work. Four other r ^\ 
NRI men work here. Am \ 
happy with my work."— *', 
Glen Peterson, Bradford J ..^ j ^ 



Ont., Canada. 



^'Am doing Radio and 
Television Servicing full 
jtime. Now have my own 
shop. 1 owe my success to 
| N.R.I."— Curtis Stath, Ft. 
Madison, Iowa. 




"Am with WCOC. NRI 
course can't be beat. No; 
trouble passing 1st class 
Radio-phone license exam." 
—Jesse W. Parker, Meri-^ 
dian, Mississippi. ■ 



"By the time 1 graduated I 
haa paid for my course, a 
car and testing equipment. 
Can service toughest jobs." 
— E. J. Streitenberger, New 
Boston, Ohio. 



AVAILABLE TO 

VETERANS 

UNDER G.I. BILLS 




Training plus opportunity is the 
PERFECT COMBINATION for 
job security, good pay, advance- 
ment. In good times, the trained 
man makes the BETTER PAY, 
GETS PROMOTED. When jobs 
are scarce, the trained man enjoys 
GREATER SECURITY. NRI 
training can help assure you more 
of the better things of life. 

Start Soon to Make $ 10, S 1S 
a Week Extra Fixing Sets 

Keep your job while training. I 
start sending you special booklets 
the day you enroll, that show you 
how to fix sets. Multitester built 
with parts I send helps you make 
$10, $15 a week extra fixing sets 
while training. Many start their 
own Radio-Television business wjtb 
spare time earnings. 

My Training Is lip-To- Date 

You benefit by my 40 years' experi- 
ence training men at home. Well 
illustrated lessons give you basic 
principles you need. Skillfully de- 
veloped kits of parts I send (see 
below) "bring to life" things you 
learn from lessons. 



You Learn by Kracticin 
with Parts I Sem 




7 



Nothing takes the place of PRACTICAL EXPERIENCE. 
That's why NRI training is based on LEARNING BY 
DOING. You use parts I furnish to build many circuits 
$ common to Radio and Television. As part of my Communi* 
cations Course, you build many things, including low power 
transmitter shown at left. You put it "on the air," perform 
procedures required of broadcasting operators. With my 
jfr^k Servicing Course you build 
t modern Radio, etc. Use Mul- 
XtsJwX tester you build to make 
AXrW A money fixing sets. Many stu- 
dents make $10, $15 week 
extra fixing neighbors' sets 
in spare time while train - 
ing. Coupon below will 
— _ bring book showing other 
equipment you build. It's 
all yours to keep. 




Television Making Good Jobs, Pre tporlty — Even without Tel* 
vision. Radio is bigger than ever. 115 million home and auto Radios 
to be serviced. Over 3000 Radio broadcasting stations use operators, 
technicians, engineers. Government, Aviation, Police, Ship, Micro-wave 
Relay. Two* Way Radio Communications for buses, taxis, trucks, etc., 
are important and growing fields. Television is moving ahead fast. 




HI 

About 200 Television stations sw now 25 million homes now have Televisic* 
on the air. Hundreds of others being sets Thousands more are being sold 
built. Good TV jobs opening up ?or ev»ry week. Get a job or have your ovsm 
Technicians, Operators, etc. business selling, installing, servicing. 

Radio-TV Needs Men of Action— Mail Coupon 

Act now to get more of the good things of life. Actual 
lesson proves my training is practical, thorough. 64-page 
book shows good job opportunities for you in many fields. 
Take NRI training for as little as $5 a month. Many 
graduates make more than total cost of training in twa 
weeks. Mafl coupon now. J. E. SMITH, President, 
National Radio Institute, Dept. 6EF, Washington 9, D. C, 
OUR 40TH YEAR. 



Goo 




MR. J. E. SMITH, President, Dept. 6EF, 
National Radio Institute, Washington 9, C. 

Mail me Sample Lesson and 64-page Book, FREE 
(No salesman will call. Please write plainly.) 



Name ..-,.,» - Age 



Address . 



City Zone. . 

\/CTC wri>a in do> * 

\§ £ I ^ of discharge 




ijf^\The Tested Way 
j^^f To Better Pay! 



www.americanradiohistorv.com 



IE AD I O - 
l:l.l:C¥IM»SICS 



Formerly RADIO CRAFT • Incorporating SHORT WAVE CRAFT • TELEVISION NEWS • RADIO & TELEVISION* 



Hugo Gernsback 

Editor and Publisher 

M. Harvey Gernsback 

Editorial Director 
Fred Shunaman 

Managing Editor 
Robert F. Scott 

W2PWS. Technical Editor 
Jerome Kass 

Associate Editor 

I. Queen 

Editorial Associate 
Matthew Mandl 

Television Consultant 
Elizabeth Stalcup 

Production Manaqer 
Angie Pascale 

Editorial Production 
Wm. Lyon McLauqhlin 

Tech. Illustration Director 
Sol Ehrlich Art Director 



Lee Robinson 

General Manaqer 
John J. Lamson 

Sales Manaqer 

G. Aliquo 

Circulation Manaqer 
Adam J. Smith 

Director, Newsstand Sales 
Robert Fallath 

Promotion Manaqer 



GERNSBACK PUBLICATIONS, 

INC. 

Executive, Editorial and Adver- 
tising Offices, 154 West 14 St. 
New York If, N. Y. Telephone 
Algonquin 5-7755. 

Hugo Gernsback 

Chairman of the Board 
M. Harvey Gernsback 

President 

G. Aliquo Secretary 



ON THE COVER 

The world's brightest incandes- 
cent lamp, with the rf equip- 
ment that powers it. The lamp 
is mounted in the rf coil under 
the oscillator. A second lamp 
is held by Miss Jean Phillips 
of Sylvania Electric Products, 
Salem, Mass. 

Color original by Larry A nkersen . 




MAY 1956 

Editorial 

The Elements of Teleducation 



Vol. XXVII, No. 5 



By Hugo Gernsback 33 



Test Instruments 

Transistorizing the Dip Meter by I. Queen 

Simplified TV Alignment ... __ by Robert F. Scott 

Chroma Probe by Fred W. Rodey 

AC-DC Probe . . by I. Queen 

Inexpensive Capacitor Checker by Norman Kramer 

The Transigner by Forrest H. Frantz, Sr. 

Television 

The Y Signal in Matrix Operation by Robert G. Middfeton 

Troubleshooting AGC Circuits, Part I by Cyrus GUckstein 

Field Service Experiences with Color TV by Charles W. Rhodes 

FM-TV Antenna Switch by R. D. Herlocker 

Industrial TV Is Simple by Edward M. Noll 

TV Service Clinic __. s by Jerry Kass 

Audio — High Fidelity 

Class B for Transistors _ _ . .by Edwin Bohr 

The Fluxvalve Pickup .by W. O. Stanton 

High-Fidelity Power Amplifiers ... by Joseph Marshall 

Servicing Home Tape Recorders, Part I . by Herman Burstein 
For Golden Ears Only by Monitor 

Electronics 

Radio-Frequency Lamp by S. C. Peek 

Control Unit for Ventilating Fans.. .by Elliott A. McCready 

Servicing the Watchmaster by Jack Darr 



Radio 

Service the Schools 



.by Yvon O. Johnson 



34 
36 
38 
39 
40 
42 



44 
46 
48 
49 
50 
53 

55 
57 
59 
75 
79 



83 
86 
90 



94 



DEPARTMENTS 








Books . 


148 




143 


Business 


141 


Question Box ,„ 


134 


Corrections 


92 


Radio Month 


6 


Correspondence 


12 


Radio- Electronic Circuits 


137 




112 


Technical Literature 


146 


New Records 


102 


Technicians' News 


106 


New Tubes and Transistors 


1 18 


Technotes 


127 


Patents 


125 


Try This One 


131 



Average Paid Circulation over 175.000 



Associate Member of Institute of High Fidelity Mfrs., Inc. 



■ • 

® 



RAD 10- ELECT RON ICS, May. 1956. Vol XXVII. No. 5. Published monthly at Mt. Morris, 111., by Gernsback Publications. Inc Second-class mail privileges authorized 
at Mt. Morris, 111. Copyright 1050 by Gernsback Publications. Inc. All rights resetTed tinder Unirers;il, International and Pan-American Copyright Conventions. 
SUBSCRIPTIONS: Address correspondence to Radio- tilecironics, Subscription Dept.. 404 N. Wesley Ave., Mt. Morris. 111., or 154 West 14 St. New York 11. N. Y, 
When ordering a change please furnish an address stencil impression from a recent wi upper. Allow one month for change ot address. 

SUBSCRIPTION RATES: U. S., U. S. possessions and Canada. $3.50 for one year; $6.00 for two years; $8. 00 for three rears; single conies 35c. Pan -American countries $4.00 
for one year: $7.00 tor two years; $9.50 for three years. All other countries $4 50 a year: $8.00 for two years; $11.00 for three years. 

££ A .^ C . H - A «9y, Ef L TISlNG OFFICES: Chicago: 1413 Howard St. Tel KOaers Park 4-8000. Los Angeles: Ralph W. Barker and Associates. 000 South New Hampshire. Tel. 
DUnkuk 7-2328. San Francisco: It lph W. Ilarker and Associates, 582 Market St.. Tel.. GArfleld 1 2481. FOREIGN AGENTS: Great Britain: Atlas Publishing and DiMrib 
uting Co.. Ltd.. London KC. 4, Australia: JlrGilPs Agency. Melbourne. France: Brentano's. Paris 2e. Belgium: Agence et Messageries de la Presse. Brussels. Holland : Yrileerron 
Hciemstede. Greece: International Rook & News Agency. Athens. So. Africa: Central News Agency Ltd. . Johannesburg ; Capetown. Durban. Natal. Universal Book Agencv Johan- 
nesburg. Middle East: Steimatz Middle East Agency, Jerusalem. India: Broadway News Centre. Dadar, Bombav #14. Pakistan: Paradise Book Stall. Karachi 3 
POSTMASTER: If undeUverahle send form 3578 to: RA D I O - ELECTRON 1 CS . 154 West 14 St.. New York 11. N. Y. Trademark registered U. S Patent Office. 



RADIO- ELECTRONICS 



www.americanradiohistorv.com 



. ' NO BARRIERS TO SUCCESS. 
Get into HIGH-PAYING 

TELEVISION 

ELECTRONICS-RADIO! 



Master all Phases with our amazing 
Shop-Method Home Training & Practical 
Equipment! We have trained Thousands 
for Big-Pay Jobs! WE WILL TRAIN YOU! 





SET REPAIR IS PROFITABLE! 

Our easy Shop-Method Lessons & 
Manuals cover this Profitable 
Field! LOW TUITION. Opportu- 
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Free Placement Assistance. Help 
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TRATED BOOK, "Your Future in 
TV-Radio-Electronics." 



OPPORTUNITIES WIDE OPEN IN THESE 

AND OTHER SPECIALIZED FIELDS! 

LoUdspeaker Systems TV-Radio Service, 

Hi-Fi, F.M., Tape Recording Installation-Repair 
Your own business Sales and Distribution 

COLOR TV & ELECTRONICS 

— America's Fields of the Future ! 
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\Z3 U7# ATTENTION DRAFT-AGE 
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training prepares you for HIGHER 
RATINGS & PAY GRADES! 



NATIONAL SCHOOLS 



TECHNICAL TRADE TRAINING SINCE 1905 
Los Angeles 37, Calif. • Chicago: 187 N. La Salle St. 
In Canada: 81 1 W. Hastings St., Vancouver, B. C. 

-L 





50 YEARS' EXPERIENCE 

training Men Like Yourself for Success! 

KNOW YOUR 
SCHOOL! These 
are the national urru I 
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from Los Angeles, recognized as a major 
"World Center of Electronics" ! 

APPROVED FOR G.I. TRAINING 
BOTH HOME STUDY AND RESIDENT COURSES OFFERED 



YOU RECEIVE THIS PROFESSIONAL 
MULTITESTER— a must for every 
Technician ! Also standard parts to 
build Receivers, Oscillators, Signal 
Generator, Continuity Checker, 
Short Wave & Standard Broadcast 
Superhet Receiver, many other 
units. All part of your course, all 
yours to keep. Mail coupon today! 
MAY, I 956 



ACT NOW! MAIL NOW TO NEAREST OFFICE! 



(mail in envelope or paste on postal card) '^H^ 
NATIONAL SCHOOLS, Dept. RG-56 T 

4000 S. FIGUEROA ST., LOS ANGELES 37, CALIF, or 187 N. LA SALLE ST., CHICAGO 1, ILL. 

Please rush FREE TV-Radio Book & Sample Lesson. I understand there 
is no obligation, no salesman will call, 

BIRTHDAY 19 




L 



NAME _ 
ADDRESS 
CITY 



ZONE 



-STATE _ 



□ Check if interested ONLY in Resident Training at Los Angeles. VETERANS: Give date of Discharge- 



j 



www.americanradiohistorv.com 




Almost without exception, makers 
of the finest high-fidelity sets 
depend upon Tung-Sol Audio Am- 
plifier Tubes to help deliver the 
performance expected of their 
products. 

Through these tubes — the "5881" 
and the "6550"— Tung-Sol clearly 
demonstrates its ability to meet 
and. maintain high-fidelity's criti- 
cal design requirements in volume 
production. 

This achievement is indicative of 
the quality and dependability 
of Tung-Sol Hi-Fi, Radio and TV 
Tubes • . . products of America's 
largest independent electron tube 
manufacturer. Tung-Sol Electric Inc. 
Newark 4, N. J. 

11 TUNG-SOL 

ELECTRON TUBES 



Tung-Sol Automotive & Electronic Products 





Radio 

month 



PORTABLE TY RECEIVER has been 
placed on the market by RCA. Only 
slightly larger than a table-model radio, 
the television set uses an 8^ -inch pic- 
ture tube hav ng a 90° deflection angle. 
The cabinet measures 10 X A inches high, 
9^4 inches wide and 12 V& inches deep. 
It weighs approximately 22 pounds, 
making it a true portable. 

The portable (shown in the photo 




I 



atop a 24-inch model) provides 36 
square inches of viewing area. Although 
the chassis contains only 10 tubes plus 
the picture tube, 4 crystals, a tube 
rectifier and a selenium rectifier, it per- 
forms 24 tube functions, making it 
comparable to many larger sets. 

BLIND RADIO AMATEUR has re- 
ceived G-E's 1955 Edison Radio Ama- 
teur Award. Sightless since birth, Rob- 
ert W. Gunderson (see photo) operates 
amateur radio station W2JIO and is 
editor pf the Braille Technical Press, 
the only monthly electronics magazine 
for the blind. 




Gunderson has invented more than 
30 types of special test instruments that 
open the electronics field to the blind 
as an occupation. A number of these 
were described by him in an article 
written for this magazine (March 
1951). His work has been directly 
responsible for many of the 600 radio 
operator licenses that have been issued 
to the blind. The Edison Award, carry- 
ing with it a check for $500, is granted 
for outstanding ingenuity and sacrifice 
in using amateur radio in the public 
interest. 

NEW COMMUNITY TV SERVICE 

has been outlined to the Senate Inter- 
state and Foreign Commerce Committee 
by Milton J. Shapp, president of Jer- 
rold. Seeking FCC permission to try 
the plan, Shapp stated that a very 
large antenna, similar to those used in 
many community television systems, 
would be placed on a mountaintop in 
the Ellensburg, Wash., area. It would 
receive uhf signals, amplify them and 
then retransmit through a directional 
horn type antenna to a receiving point 
in the valley. The transmitter would 
operate on 1/10 watt. The received sig- 
nal is converted to vhf before it is fed 
into the coaxial cable for home receiver 



COLOR TELEVISION, computer ad- 
vances, space electronics, scatter prop- 
agation and medical electronics key- 
noted the 1956 IRE convention held in 
New York City March 19-23. Attend- 
ance was over 40,000, a startling figure 
for a convention that opened in the 
midst of the worst blizzard the north- 
east section of the country has seen for 
many years. 

Some 275 technical papers were read 
at 55 sessions. Color picture tubes 
received great attention. Several types, 
including Philco's mysterious Apple, 
were the subject of papers. Tape re- 
cording of color was the subject of five 
papers. The session on the Earth 
satellite program attracted more than 
2,000 people, jamming the meeting hall 
and necessitating two overflow meet- 
ings. Zworykin, of television fame, told 
the delegates how computer techniques 
could improve medical diagnosis. 

Exhibitors occupied 714 booths, show- 
ing everything from a ^-ton radar 
antenna to a 3-transistor amplifier with 
a gain of 70 db, yet occupying a space 
of only 5/16 x 3/16 x % inch, smaller 
than many single transistors. Philco 
M-l's were the units used in this par- 
ticular amplifier. 



RADIO-ELECTRONICS 



Miniature Seal 
lamps Hec 




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° ^ r ° 

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MERIT, first in exact and 
universal replacement 
transformers, yokes, coils 
—the only manufacturer 
of transformers, yokes and 
coils who has complete pro- 
duction facilities for all 
parts sold under their 
brand name. 





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SKOGMO, MONTGOMERY 
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single source for all your transformer 
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Merit 

Merit Coil & Transformer Corp. 
4427 North Clark Street 
Chicago 40, Illinois 




THE RADIO MONTH 

PORTABLE TV TRANSMITTER has 

been unveiled by the U.S. Signal Corps. 
Weighing only 8 pounds, the camera 
can be easily held in the hands like a 
home movie camera. The transmitter, 
complete with built-in power supply, 
weighs 47 pounds. 

Freed for the first time from cum- 
bersome cable connections that har- 
nessed him to a source of power, the 
Signal Corps cameraman (see photo) 
can now reach previously inaccessible 



( Continued) 




spots — through forests and hedgerows, 
over ditches, etc. The camera can also 
be left unattended in dangerous areas. 
The voice accompanying the picture is 
handled by handy-talkie radio. In recent 
tests pictures a mile away were picked 
up by the camera and transmitted V 2 
mile to a television receiver mounted in 
a jeep, the jeep's electrical system sup- 
plying power for the receiver. 

The transmitter can operate con- 
tinuously and unattended for 2 hours 
from a five-cell rechargeable silver- 
zinc battery about one-third the size 
and weight of a car battery. Push- 
button controls at the jeep permit 
monitoring several cameras in the field. 

TOLL-TV TRIAL has been urged by 
Federal Communications Commissioner 
Robert E. Lee. Writing in Look maga- 
zine, he said he was convinced that 
endless legal procedures, hearings and 
studies will never answer the questions 
of whether the public wants pay-as- 
you-see TV and will support it, 

Lee proposed that the FCC adopt the 
following program: Approve subscrip- 
tion TV on a broad basis, leaving it up 
to the individual to choose the system 
he wishes to use; apply some tempo- 
rary restrictions to toll TV, such as 
limiting it initially to uhf stations; 
permit the trial period for toll TV to 
continue long enough to test public re- 
action truly; permit stations to drop 
toll TV if they find it does not fill a 
market need in their own area. 

He stated further that these views 
are strictly his own and do not reflect 
the opinion of the commission, which 



Calendar of Events 

79 th Convention of Society of Motion 
Picture & Television Engineers, April 29- 
May 4, Hotel Statler, New York City. 

1956 Electronic Components Symposium, 

May 1-3, Department of Interior Audi- 
torium, Washington, D. C. 

1956 Electronic Parts Distributors Show, 
May 21-24, Conrad Hilton Hotel, Chicago. 
(A closed show for distributors, manufac- 
turers and their representatives. Kadio- 
Electronics will exhibit in Room 632. 

RETMA Symposium on Reliable Applica- 
tions of Electron Tuhes, May 21 22, Irvine 
Auditorium, University of Pennsylvania, 
Philadelphia, Pa. 



presently has the subject under con- 
sideration. 

GIANT RADIO TELESCOPE capable 
of detecting celestial objects at dis- 
tances close to the limits of the observ- 
able universe will be constructed near 
Delaware, Ohio. Work on the super 
radio telescope is scheduled to start 
late this spring with a grant of $48,000 
from the National Science Foundation, 
Washington, D.C., to the Ohio State 
University electrical engineering de- 
partment. The site is near Perkins 
Observatory, operated jointly by Ohio 
Wesleyan and Ohio State universities. 

The reflecting type radio telescope 
will be about 700 feet long and 75 feet 
high, making it the largest of its kind 
in the world. Actually, the telescope is 
a giant radio antenna which receives 
radio emanations from the heavens 
much as an optical telescope receives 
light waves. 

The antenna system will include a 
parabolic reflector and a flat, tilt- 
able reflector to deflect radio waves 
from the sky into the curved portion, 
which in turn will focus the waves into 
a large metal horn. The horn will fun- 
nel the waves into an ultrasensitive re- 
ceiver to be housed in a small building. 

THREE NEW TV STATIONS have 
gone on the air since our last report: 

KINY-TV Juneau, Alaska 8 

WDMJ-TV Marquette, Mich 6 

WAST Hagaman, N. Y 29 

WIRK-TV West Palm Beach, Fla., 
channel 21, and WTAO-TV Cambridge, 
Mass., channel 56 have gone off the air. 

KULA-TV, Honolulu, T. H., channel 
5, will change its call letters to KTCA, 
effective June 1. 

COSMIC RAY BOMBARDMENT, 

the greatest ever recorded on earth, 
began pouring on the earth around Feb. 
22, following a tremendous flare on the 
surface of the sun which scientists 
estimated was equal in force to l,000 r 
000 hydrogen bombs. 

They said it was the first clear evi- 
dence that radio waves were somehow 
associated with the production of cos- 
mic radiations. The bombardment inter- 
rupted network radio communications 
between Rome and London and New 
New York and crippled shortwave com- 
munications throughout the world. END 

RADIO-ELECTRONICS 



www.americanradiohistorv.com 




your source of finest TV and Radio Tubes is 



first in transistors.. i 




Raytheon's pioneering in the research, de- 
velopment and production of Transistors has re* 
suited in many important "firsts" — firsts that give 
Raytheon an unchallenged lead in the field. 
Here are some of these finsts: 

FIRST In commercial production. "Raytheon was the first company 
to commeradlfy produce and sell function transistors. These firsf transis- 
tors set high performance standards as they revolutionized the hearing 
aid, industry. 

FIRST In RF Transistors. Raytheon scored another important first 
by leading the way in RF Transistors, too. The first Commercially pro- 
duced RF Transistors — Raytheons — are revolutionizing the portable 
radio industry, and are being used in computers and communication 
equipment. Many major manufacturers of portable radios use these 
Raytheon RF Transistors and all "hybrid" portables use either Raytheon 
Transistors, Raytheon Subminiature Tubes or a combination of both. 

FIRST in PNP Silicon Transistors. Raytheon alone makes a line 
of PNP Silicon Transistors that fills the need for transistors that will op- 
erate at high temperatures. 

FIRST Mafor Manufacturer to Break the Dollar Barrier. A 

most important first to you — Raytheon is the first major supplier to 
achieve such high production and product acceptance of their transis- 
tors that one of the line could be priced at less than a dollar — 
Raytheon quality transistors range in price from 99*. 

At Raytheon more than 100 engineers and scientists, plus nearly 1400 
other employees are devoted to a single task — the design, develop- 
ment and production of the finest and best in transistors and diodes. To 
help them work more efficiently, and to meet increasing production 
schedules Raytheon recently added facilities totaling three acres of 
engineering and manufacturing space to its Semiconductor Division. 

Raytheon Tube Distributors from coast to Coast stock and recommend 
Raytheon Transistors. 

RAYTHEON TRANSISTORS 

more in use than all other makes 



This huge plant (3 acres of 
floor spece) has just been 
added to Raytheon's Semi- 
conductor Division , — to 
help meet th-s ever increas- 
ing demands for Raytheon 
Transistors. 



combined ^^J^lSte 





RAYTHEON MANUFACTURING COMPANY 

Receiving and Cathode Ray Tube Operations 
Newton, Mass. • Chicago, III. • Atlanta, Ga. • Los Angeles, Calif. 

lr II th ^ Receiving and Picture Tubes, Reliable Subminiature and Miniature Tubes^ 

Raytheon makes all these: ^ $emjconductor Diodes Cind Transistors, Nudeonic Tubes, Microwave Tubes. 
Visit Raytheon Booth No. 4 at the ELECTRONICS PARTS DISTRIBUTORS SHOW May 21-24 — Badges issued only in advance— No registration at the show 
MAY, I 9 5 6 9 



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Service Technicians will tell you 
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HERE'S PROOF FCC LICENSES ARE OFTEN SECURED IN A FEW HOURS OF 
STUDY WITH OUR COACHING AT HOME IN SPARE TIME 
Name and Addreu License Time An 

A/1C Ronald H. Person, St. Louis 20, Mo 1st Class 25 weeks Approved 

Milton L. Geisler, ET3, FPO, San Francisco, Calif 1st Class 26 weeks Member 

Marvin F. Kimball, Lafayette, Ind 2nd Class 21 weeks 

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John E. Hutchison, Bluefield, W. Va 1st Class 27 weeks 

CIRE IS THE ONLY HOME STUDY SCHOOL WHICH SUPPLIES FCC-TYPE 
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CLEVELAND 3, OHIO 



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Here are a few recent examples of Job-Finding results: 




ELECTRONICS TECHNICIAN 

'I am now employed by the Collins Radio Company 
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James A. Wright, Beltsviile, Md. 



MAY, 1956 



INDUSTRIAL ELECTRONICS 

"Upon my discharge from the Navy I used your 
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(final checkout)." 

Glen A. Furlong, Fresno, Calif. 

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Look what RADIO-ELECTRONICS 

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• ELECTRONICS IN THE A IK FORCE 

By Aaron Naden 

• COLOR DEMODULATOR ALIGNMENT 

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• TRANSISTOR RADIOS — A SURVEY 

By I. Queen 

• A UNIVERSAL EXPERIMENTAL CHASSIS 

By Kurt Freund 

• WAVEKORM GENERATOR 

By Ed Bukstein 

• AUDIO TRANSFORMERS 

By Norman H. Crowhurst 



• UNDERSTANDING COLOR RAR 
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• TURE-TESTER SETTINGS FOR 
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By E. N, Kaufman 

• HIGH-GAIN TRANSISTOR AUDIO 
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• PHOTOELECTRIC LIGHT COMPUTER 
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Correspondence 





SYNTHETIC MUSIC 

Dear Editor: 

On receiving the March issue of 
Radio-Electronics my attention was, 
naturally, captured by the article 
"Synthetic Music via Electronics," by 
Sol Heller. 

I have for some months now, had 
the RCA Victor LP record L.M. 1922 
Experimental which demonstrates many 
of the capabilities of this electronic 
music synthesizer. This, however, is 
unfortunately not mentioned in Mr. 
Heller's article. Anyone interested in 
this subject should by all means get 
the record for it demonstrates clearly 
the advantages and at least the present 
limitations of this method for produc- 
tion of music without performing 
artists. No doubt many improvements 
will be made so that most if not aH 
of the subtle artistry of performing 
artists will "be well simulated^ The 
practical aspects of this development 
may, however, be impeded from un- 
expected quarters— for example, Mr. 
Petrillo! 

My own interest might best be ex^ 
pressed by a prophetic quotation of the 
two concluding paragraphs of my 1936 
paper "Electronic Music and Instru- 
ments," published in Proceedings of 
the IRE, Vol. 24, No. 11, pp. 1427-63: 

"The ideal instrument is one which 
can make any sound known, unknown 
or conceivable; to do this we must 
provide a generator for periodic vibra- 
tions embracing the whole audio spec- 
trum of frequencies. We must be able 
to select from this generator at will any 
desired single frequency or many single 
frequencies simultaneously, whether 
harmonically or inharmonically related 
or whether in narrow or wide contin- 
uous bands. We must further be able 
to emit these frequencies in any desired 
sound amplitudes and envelope shapes, 
even though, in a given sound, all the 
components require different shapes of 
envelope. We must be able to control 
the emission of these sounds by some 
suitable playing technique and appara- 
tus. 

"With such an apparatus we shall 
be able to synthesize any possible sound, 
continuous, damped, transient, musical 
or nonmusical, for we have all the 
elements of sound and means for put- 
ting together any desired combination 
of these elements in any desired time- 
amplitude relationship." 

Benjamin Franklin Miessner 
Miessner Inventions, Inc. 
Morristown, N, J. 



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CORRESPONDENCE (Continued) 

LIKES OUR ARTICLES 

Dear Editor: 

"Those Deadly Intermittents," on 
page 98 of Radio-Electronics, Decem- 
ber, 1955, made very refreshing reading 
on this side of the Atlantic. It is indeed 
encouraging to learn that dealers and 
service technicians on your side expe- 
rience the impatience and irritation of 
viewers when their TV gives out on 
them. Televitis is a terrible modern 
complaint which calls on all one's re- 
sources to combat. It is a boost to 
self-confidence to learn that a similar 
technique to what we have developed 
here is successful in dealing with serv- 
ice complaints. Some unenlightened 
people look askance on practices which 
start with "bottle-tapping" and cus- 
tomer interrogation, but surely this 
seems to be the quickest and surest 
way of getting at the trouble. 

F. E. Dyer 

Sheffield, England 

A CASE AGAINST LICENSING 

Dear Editor : 

May I answer John Wheaton's article 
titled, "Licensing — Bad or Good," 
which appeared in your January issue? 
I am opposed to licensing in any 
form! This subject has occupied my 
attention the past 4 years and all the 
statutes which Mr. Wheaton mentions 
are in my file and have been read by 
me carefully. What he failed to men- 
tion — and most certainly it should be 
highlighted — is one thing all these laws 
have in common — punitive and vindic- 
tive features. They hold the threat of 
heavy fines and imprisonment over 
those who come under their control and 
contain license-revoking powers. 

As a small, independent shop owner, 
it has always been my belief that "He 
governs best who governs least." There 
are of course those vocations like law, 
dentistry and medicine whose com- 
plexity and impact on our daily life 
require that those who follow them 
need to give proof of their fitness and 
training. (It would make interesting 
reading indeed if some people could 
tell of their experiences at the hands 
of these licensed gentry.) 

But why, why, this insistent demand 
for licensing radio and TV men? Is it 
really to exclude the part-time operator, 
the incompetent; to shackle and get 
rid of the chiseler and the cheat? Or 
because of so-called excessive charges? 

In the spring of 1953, when the art 
was newer and I was gathering mate- 
rial to fight a licensing attempt in 
Illinois, I wrote to Better Business 
Bureaus in representative cities asking 
their experience about television com- 
plaints against service technicians. As 
a comparison I wrote in the spring of 
1955 to these same BBB offices and 
received the information that com- 
plaints generally had diminished sharp- 
ly; that the public was pleased with 
the technical abilities of service tech- 
nicians, and that charges generally 
were not excessive. You may also re- 
(Continued on page 18) 

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learn-by -Doing "A// the Way" 

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them. You do more than just build circuits. 
You get practice recognizing, isolating, and 
fixing innumerable troubles. 

You get actual experience aligning TV 
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UHF & COLOR TV Making New Boom 

Installing front-end channel selector strips 
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To cash in on the coming color TV boom 
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CORRESPONDENCE (Continued) 
call that RCA conducted a Roper poll 
and found the same answer. 

What then lies in back of this clamor 
to license you and me? The sad fact 
is that smart and capable technicians 
are being' swayed into aiding and 
abetting this legislative stupidity for 
which there is no real need. They are 
selling themselves a bill of goods. They 
think that by putting a legislative 
straitjacket on their competitors, their 
own troubles will disappear like mist 
in the morning sun. The chiseler can 
never be eradicated by legislation; he 
is a disease that you have to learn 
to live with. Licensing yourself may 
well put you out of busine'ss however. 

Let me point out how a license 
law can be a constant threat to your 
livelihood. Making a living in one's 
chosen field in this country should be 
a right and not a privilege granted by 
statute. 

In that great body known as the 
public move all kinds of people includ- 
ing the chiseler, the hater, the trouble- 
maker, the "there ought to be a law" 
type of individual. These particular 
people are always looking for a chance 
to throw their weight around. A 
licensing law is made to their order. 
You can plate your service work with 
the golden sweat of honest effort and 
knowledge of a job well done but these 
people give you the rap every time. 

Then you will have the commission, 
or jury, or whatever you will choose 
to call the public body appointed to 
oversee the law and hear the complaints 
brought against you. You are a small 
shop operator and a member of the 
public complains to this group that you 
have done him wrong. You have to 
close your shop and come before this 
group to answer that complaint. It is 
dismissed. But there will be others. 
In time you come to live in fear of 
such injustified accusations for which 
you must answer to a jury. 

The time can come when the license 
body will say to you, "Mr. Service 
Technician, we have had numerous 
complaints about you. True, they have 
all been dismissed, but we feel that 
there must be some basis for these 
accusations and we are compelled to 
put you on probation. Many more such 
complaints and of necessity we will 
have to revoke your license in the public 
interest." From then on, brother, you 
are on borrowed time! 

These public commissions must have 
a record of positive accomplishment. 
At the start they may bend over back- 
ward to be impartial but as time goes 
on they simply sink into the slough 
where all such agencies land — bureau- 
cratic indifference. They are out to 
show the public how well its interest 
is defended, and you are the goat. If 
the continued attrition and pressure of 
needless complaints and appearances 
to defend yourself won't force you to 
throw in the towel, they will. 

Howard Wolfson 
Chairman, Associated Radio & TV 

Servicemen 
Chicago, III. 



RADIO-ELECTRONICS 



PHAOSTRON INSTRUMENT AND ELECTRONIC COMPANY 
151 PASADENA AVE., SOUTH PASADENA, CALIF. 



www.americanradiohistorv.com 



ME N 17-55! 

HERE'S A NEW 
OPPORTUNITY 
FOR YOU! 





PREPARE AT HOME FOR A 
PROFITABLE CAREER IN 



ELECTRONICS 



Get in on the Ground Floor of this 
Fnst-Iflouing Field 




Woof a better job? . . . more money? . . . better 
working conditions? These are the things that can 
come to a man when he has a skill to offer . . . 
especially when that skill is in a newer field where 
ground floor opportunities often lead to well- 
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applications to AUTOMATION — and what a field! 

Many plants, large and small, in various parts 
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a better product and at lower cost. This equipment 
must be designed, installed and maintained — 
calling for well trained men. That's where YOU 
may come in! 

You need no special technical experience . . . 
no previous knowledge of Automation Electronics 
... to prepare for a future that can be bright and 
more secure. For now there is a proved way to get 
this important know-how. Mail coupon for com 
plefe details. Men 17 to 55 preferred. 

WHAT IS AUTOMATION ELECTRONICS? 

Simply stated, this refers to the marvelous elec- 
tronic controls that will help regulate the much 
talked about "automatic factory" — as well as other 
amazing automatic equipment in plants, offices 
and elsewhere. It is a gateway to some of the 
most desirable opportunities in the amazing, newer 
field of Automation. 



A New Training Program! 

As one of the leoding organizations of 
its kind, the DeVry Tec meal Institute 
has years of experience in teaching 
Electronics, Television and Radio. So it 
is only natural for this training institute 
to develop a new program to prepare 
men for good jobs in instrumentation — 
as well as in the design, installation and 
maintenance of Electronic controls — 
as applied to Automation. 

EMPLOYMENT SERVICE 

Following the same proved method 
used to train thousands of other men, 
you get valuable practical experience 
from actual electronic equipment. You 
also receive well-illustrated texts and 
effective moving pictures to show im- 
portant basic principles — a wonderful 
home training advantage! To top that 
off, D T I provides actual employment 
help when you hove completed the 
training— all of which can open the way 
to many new and exciting opportunities. 
Member of 
National Home Study Council 



Recording and billing 




Anti-aircraft gun control 




Traffic control signals 




ONE OF AMERICA'S 
FOREMOST ELECTRONICS 
TRAINING CENTERS 



r in 



DeVRT TECHNICAL INSTITUTE 

CHICAGO 41, ILLINOIS 

FORMERLY 

deforest s training, inc. 



MAIL THIS COUPON TODAY! 



I DeVRY TECHNICAL INSTITUTE, Dept. RE-5A-M 

4141 Belmont Avenue, Chicago 41, III. 

I would like further information about the newer Electronic opportun- 
ities in AUTOMATION, also facts on how you may help me to prepare. 



I 




Pleate Print 



Age_ 
-Apt- 



Zone- 



_5tate_ 



DTI's training is available in Canada 



MAY, 1956 



19 



www.americanradiohistorv.com 




LIVING SOUND" IS YOURS TO ENJOY 
WITH NORELCO O^cM&A 



FULL RESONANCE TWIN-CONE SPEAKERS 




High fidelity and tonal qualities associated with 
expensive multi-unit speaker systems- 
are similarly produced with new 
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Norelco's exclusive Twin Cones are made from 
specially selected and matched materials — 
operated from the same magnet and voice coil 
— some covering an extremely wide range 
up to 20,000 c s. Norelco's twin-cones arc always in 
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degree of efficiency under all conditions. 

Unequalled manufacturing precision and quality is 
inherent in all Norelco speakers. All component 
materials — including magnets, wire and even 
cone materials — are manufactured and assembled 
by Philips to suit a specific speaker design. 

Many sizes in standard impedances arc available 
from your dealer or send to Dept.D-5 today for 
more details. Norelco FRS speakers are 
priced from $59.98 to $9.90 audiophile net. 





20 



Add to... and improve any sound system 
with 

*FULL RESONANCE SPEAKERS 

NORTH AMERICAN PHILIPS CO., INC., 100 East 42nd Street, New York 17, N. Y. 

RADIO. ELECTRONICS 



www.americanradiohistorv.com 



THEY SAID HE COULDN'T LEARN TV AT HOME 



but now 



repairs theii 

Read this letter from 
one of my students 




L C. Lane, B.S., M.A. 

President, Radio-Television 
Training Association. 
Executive Director, Pierce 
School of Radio & Televisi 



I CAN DO FOR YOU WHAT 
DID FOR THIS MAN ! 



iftg? -te C ~ 

Television-Kadio-tlectronics neia |ust as rms i in **re*Jy j b * o ut "re for «*a ^ the b2£."*oj| 

man did. My easily understood lessons- / future and i e £ a *JiW a J** 8 to fc^e 

especially prepared for home study - can / vfem^ into 'S* I g | t ? "S Ration 

bring you the same success they brought hun- / ^ttie tiVi^bii^Jast t el 2 ^ TV r a j? ear 

dreds of men, many of them with no more than / " e <* " SSS ^ 

time r 1 s tudvin? u & fflanv hor t ye*r> 



txecurive uirecror, nerce ■ rtir} COD THIS mara i 

School of Radio & Television. i rWK mMPl I 

YOU can get top pay in the fast-growjng 
Television-Radio-Electronics field just as this 
man did. My easily understood le 

1 1\/ nronnrorl ffir hftlTie Stud 1 

f brou< 

*\ no more inuii 

HARM BY DOING • 




CombinonenValtm.fr- ■ D ^SChl 7. ^Srat^i^ I 

m— m»— i« Jg> IM|JML 'fas ter, p. J • " / 

^^^*TP53^F Public Address System N | ' J P a 55 | 

* MF Si9no, Cmro,or g J *f ^^^J 

al parts and equipment I send you as 21 -inch. (10-inch tube furnished. Slight extra cost for larger 

. You get enough equipment to set up sizes.) . . . Also a Super-Het Radio Receiver, AF-RF Signal 

oratory and prepare for a top-pay TV Generator, Combination Voltmeter- Ammeter -Ohmmeter, 

keep an Electromagnetic TV RECEIVER C-W Telephone Transmitter, Public Address System, AC-DC 

>ered to take any size picture tube up to Power Supp ly. Everything supplied, including all tubes. 

OACHING COUS^^^HH I FREE I VETERANS 

5 d a v mcc re**, err ll.~or.co n^P^ff! - ™ My school folly approved to train Veterans under new 

Korean G.I. Bill. Don'! lose your school benefits by 
waiting too long. Write discharge date on coupon. 




part ot your course, tou geT enougn ^ 
your own home laboratory and prepare 
job. You build and keep an Electromagi 
designed and engineered to take any size 

FCC COACHING COURSI 

Important for BETTER-PAY JOBS requiring FCC license. 
You get this training AT NO EXTRA COST! Top jobs go to 
FCC-licensed technicians. 

CHOOSE FROM THREE COMPLETE COURSES 

covering all phases of Radio, FM and TV 
RADIO-FM-TELEVISION TECHNICIAN COURSE -no previous experi- 
ence necessary. 

FM-TV TECHNICIAN COURSE — previous training or experience in 
radio required. 

TV CAMERAMAN AND STUDIO TECHNICIAN COURSE - advanced 
training for men with Radio or TV training or experience. 

EXTRA TRAINING IN NEW YORK CITY AT NO EXTRA COST! 

After you complete either the Radio-FM-TV Technician or the FM-TV 
Technician course you get two weeks of Lab work on modern electronic 
equipment at our associate resident school in New York City, Pierce 
School of Radio & Television. Available if you want it— AT NO EXTRA 
COST WHATSOEVER! 

Jaitfr ton ^tamt^9 J^^^fet 

52 EAST 19th STREET • NEW YORK 3 f N. Y. 

Licensed by the State of New York • Approved for Veteran Training 
MAY, 1956 



I'll send you my 
new 40-page book, 
"How ta Make 
Money in Televi- 
sion, Radio, Elec- 
tronics/* a Free 
sample lesson, and 
other literature 
showing how and 
where you can get 
a top-pay job in 
Television. 



MAIL THIS COUPON TO 



■MB ill 



Mr. Leonard C. Lane, President 
RADIO-TELEVISION TRAINING ASSOCIATION 

Dept. R-5C, 52 Eojt )9th Street, New York 3, N.Y 
Deor Mr. Lone: Send me your NEW FREE BOOK, FREE 
SAMPLE LESSON, and FREE aid* that will show me 
how I con moke TOP MONEY IN TELEVISION. I under- 
jtond i om under no obligation. 

(PLEASE PRINT PLAINLY) 



City 

I AM INTERESTED IN: 
Q lodia-FM-TV TetnnUion C©vM« 
□ FM-TV Technician Count 
Q TV Cameraman 4 Studio 



_Zone_ 



_Stott_ 



VETERANS! 



Write discharge dat« 



in 



NO OBLIGATION! 



21 



www.americanradiohistorv.com 




honorable ancestor of the UNIVAC 



In theory many -centuries have gone into the 
development of the Univac? Only recently, at 
Remington Rand Univac, has it achieved prod- 
uct perfection. The tremendous strides forward 
in the past few years are due to the imagina- 
tion and creative genius of the scientists and 
engineers of Univac. Recognized leaders in the 
field of electronic computer systems, they are 
the men who set the standards for others to 
follow. You can become a member of this team 



Send complete resume to 
# 




. . . where ambition and professional skill find 
their reward in limitless opportunities in an 
expanding organization. 

Immediate openings for: 

FIELD LOCATION ENGINEERS with a college de- 
gree in a scientific or engineering field and experi- 
ence in electronics. Extensive electronic back- 
ground may substitute for some college. Many 
opportunities fqr rapid advancement. 

FIELD LOCATION TECHNICIANS with technical 
school background and preferably some experi- 
ence in electronics. These positions can lead to 
full engineering responsibility. 



Registered in U. S. Patent Office 



Dl Vrs 1 0 N OF S PER RY RAND CORPORATION 

— AT ANY ONE OF THESE THREE PLANT LOCATIONS- 



MR. D. A. BOWDOIN 
Dept. MP- 13 
2300 W. Allegheny Ave. 
Philadelphia, Pa. 



MR. KURT PINKE 
Dept. MS-10 
1902 W. Minnehaho Ave. 
St. Potl W4, Minn. 



MR. FRANK KING 
Dept. MN-10 
Wilson Avenue 
South Norwatk Conn. 



www.americanradiohistorv.com 



Send for FREE booklet ana 




in RADIO-TV- 
ELECTRONICS 

What would a $10 or $20 
a week raise mean to you 

Think of it! Only one $IO-a-weelc raise will 
your investment in CREI training, and leave 
profit of $200 or more the very first year 
increases in pay thereafter are all pure pro 
you'll be prepared for many more pro- 
motions and pay raises in the future 
years of your life! 

CASH IN ON THE BIG PAYOFF! 

Why let opportunity to make more 
money pass you by because of lack of 
training? This booklet describes in de- 
tail how CREI training equips you 
quickly at home to forge ahead into a 
good paying job — in TV (color, too) — 
industrial communications — research — 
aeronautics and scores of other fields in 
this mushrooming industry. 

CREI Training Means Promotion, 
Pay Increases Within a Short Time 
Here are just a few letters received 
from CREI students: 
"In this time of less than two years, I 
have almost doubled my salary and have 
gone from wireman to engineering as- 
sistant and now to junior engineer. I 
have CREI to thank."— Frank A. Eck- 
ert, 22 Clover Lane, Levittown, Pa. 
"I chose CREI training upon rec- 
ommendation of two top engi- 
neers. Before I completed the 
course I became transmitter chief 
of a 5KW station. I am now em- 
ployed as a technician at a 100 
KW TV station and in spare time 
have a good TV sales and service 
business Arlie D. Patton, 203 
Burke Ave., San Antonio, Tex. 

CREI TEACHES YOU WHAT 
INDUSTRY WANTS 

Industry recognizes this, by 
choosing CREI to train their own 
technical staffs. Among them: 
United Air Lines, Canadian 
Broadcasting Corporation, Sears, 
Roebuck & Co., Bendix Products 
Dhision, All America Cable and 
Radio, Inc., Radio Corporation of 
America. 

CREI GRADUATES GET TOP JOBS 

... as electronic engineering tech- 
nicians. Employers contact us 

regularly for graduates to fill | CHECK: □ Home Study n 
good jobs. Our placement bureau 




fit, 



cannot keep up with the demands. Typi- 
cal recent requests: "Two openings in 
our Field Service . . . aircraft electron- 
ics .. . starting salary is $380 and up 
. . — North American Aviation, Inc., 
Columbus, O. 

"Just about four months have passed 
since I made my first recruiting trip to 
CREI. As a result of that visit Messrs. 
Kohs, Plante and Wenger are now mem- 
bers of the Laboratories and Mr. Kres- 
ge soon will be . . . we have some open- 
ings now and will have others . . — 
Bell Telephone Laboratories, Murray 
Hill, N. J. 

NAME YOUR GOAL! 

CREI training equips you to pass FCC 
exams, qualify for top jobs; or, start 
your own business — many a graduate 
has been launched on a successful, self- 
owned business career, thanks to CREI 
training. 



CREI ALSO OFFERS 
RESIDENCE TRAINING 

CREI Residence School in Washington 
offers instruction at same high techni- 
cal level. Classes start frequently. 
Qualified residence school graduates 
earn degree: Associate in Applied 
Science. Check coupon if you prefer 
residence study. 

WHY WAIT? YOU CANT LOSE! 

You already have practical experience. 
Add to it CREI's advanced training and 
be assured of excellent pay, a bright fu- 
ture and job security in all electronics 
fields. 

You owe it to yourself! Fill out coupon 
and mail today. No obligation. You'll 
receive your copy of "Your Future in 
the New World of Electronics" right 
away — free. Send for it today! 
AVAILABLE TO VETERANS UNDER Gl BILL! 



FILL OUT AND MAIL TODAY— BEFORE YOU FORGET IT! 



CAPITOL RADIO ENGINEERING INSTITUTE 

Accredited Technical Institute Curricula Founded 1927 

Dept. 145-C, 3224— 16th St., N. W., Washington 10, D. C. 

Please send me your course outline and FREE illustrated Booklet 
"Your Future in the New World of Electronics" . . . describing 
opportunities and CREI home study courses in Practical Elec- 
tronics Engineering. 



CHECK 
FIELD OF 
GREATEST 
INTEREST 



□ Practical Radio Electronics Engineering 

□ Broadcast Radio Engineering (AM, FM, 

□ Practical Television Engineering 

□ Aeronautical Electronics Engineering 



To help us answer 
quest intelligently, 
give the following 
tion: 

EMPLOYED 
BY 

TYPE OF 
PRESENT WORK 



your re- 
please 
informa- 



TV) 



Name . 

Street . 

City. 
CHECK: 



. Zone State 

Residence School □ Korean Veteran 



SCHOOL 
BACKGROUND 



ELECTRONICS 
EXPERIENCE 



IN WHAT BRANCH OF ELECTRON- 
ICS ARE YOU MOST INTERESTED? 



MAY, 1956 



23 



www.americanradiohistorv.com 



PRODUCTION TECHNIQUES: 

for the 
manufacturing of 
High Reliability 
Capacitors 



To produce capacitors free from any possibil- 
ity of latent defects, for use in the most critical 
applications, the Sangamo Electric Company 
has recently intensified its high reliability 
program of fabrication and inspection 
methods. 

Incoming materials are rigidly inspected to 
meet stringent high reliability standards and 
are stored in areas where temperature, humid- 
ity and dust are controlled at all times. 

Complete production histories are kept on the 
basis of small capacitor lots. X-raying of 
individual units, heat tests, vibration tests, 
altitude tests, and total destruction tests of a 
given percentage of all finished units assure 
components with an extremely low AQL. 
Testing facilities and resultant performance 
characteristics are far in excess of military 
specifications. Specify these high reliability 
capacitors for your critical applications. 

SANGAMO ELECTRIC COMPANY 

MARION ILLINOIS 



it ff? 




Separate facilities are maintained loi the exclusive processing and manufacture- of high relia- 
bility capacitors- Only specially trained, highly skilled operators, who wear special clothing to 
prevent any possible source contamination, w»rk here. 




Oil-filled capacitors are subject to vacuum under elevated temperatures, 
ihen are individually examined to insure complete hermetic seal. 



TOP performance 
for TV anywhere 1 . 

Federal's 



High Volume-Low Price TV Lead-in 



MM 



ALL-STAR 

LEAD-IN TEAM 

Urban, fringe or distribution system • . • 
heat, rain, dust, snow, ice, salt spray, 
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you'll find a winner in these dependable, 
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North, East, South, West . . . wherever there are TV cus- 
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These six popular types are outstanding examples of 
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Federal lead-ins can be installed with utmost confi- 
dence, because they are engineered and manufactured by 
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Check the high points of Federal's "All-Star" Team 
...check your stock of TV lead-ins.. .get in touch with 
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"America's leading producer of 
solid dielectric cables" 





Economical and Efficient 
TV-U90— 300-ohm heavy-duty lead-in 
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cient. Insulated with Federal-devel- 
oped "silver" polyethylene for long 
life. Also available in brown- 



Another Low-cost Leader 

TV.2000- 300-ohm dumbbell-shaped 
lead-in with 55 mil. web. Has 7/#30 
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cost type for the average installation. 
Cinnamon-brown color is protection 
against ultra-violet. 

'Quality-Controlled'' TV Lead-in & Cable 




Heavy-duty Type 

TV.11 82— 300-ohm deluxe type heavy- 
duty long life lead-in with 7/#28 
copper strands, 100 mil. web. Avail- 
able in "silver" or brown polyethyl- 
ene. Resists weather, heat, sun. Very 
low line loss in fringe areas. 



, M— . 

Quality plus Economy 
TV-1 184 -300-ohm dumbbell-shaped, 
standard, economy type lead-in with 
7/#28 copper strands, 70 mil. web, for 
urban areas with no unusual condi- 
tions. Cinnamon-brown color is high- 
ly effective in resisting ultra-violet. 



Rotor Lead-in 
TV-l 188 -Rugged, dependable, long- 
life rotor lead-in. Weather-resistant. 
Insulated with "silver" vinyl. Three 
7-strand conductors of .0121 AWG 
soft bare and one conductor of .0121 
AWG tinned soft bare. 



Community TV Lead-in 



Secondary Lead-in 

59/U Type — 73 -ohm coaxial lead-in 
Highly efficient as a Community TV 
pole-to-house tap-off. Meets all needs 
wherever a high-grade installation is 
a must. Ideal for use with unbalanced 
input TV receivers. 



For data on other types, write Dept. D-463 A 



Federal Telephone and Radio Company 

A Division of INTERNATIONAL TELEPHONE AND TELEGRAPH CORPORATION 
COMPONENTS DIVISION • 100 KINGSLAND ROAD • CLIFTON, N. J. 

In Canada : Standard Telephones and Cables Mfg. Co. (Canada) Ltd., Montreal, P. Q. 
Export Distributors: International Standard Electric Corp., 67 Broad St., New York 



MAY, 1956 



25 



www.americanradiohistorv.com 







3 9 9 



HERE'S PROOF 



your 

customers 
want 

CBS tubes 

Since Garry Moore has been selling 
CBS tubes over the CBS Television 
Network, most service technicians 
have had women customers ask them 
for CBS tubes. And not just once in 
awhile. 

Every day more and more women 
are requesting CBS tubes. We hear 
stories like Mrs. Svensson's often. 

It all adds up to these important 
facts. You build good will , . . cut call- 
backs . . . and profit more when you 
install CBS tubes ... the tubes with 
the Good Housekeeping Guaranty Seal. 

Is your caddy well stocked with CBS tubes? 




CBS-H YTRON 

Danvers, Massachusetts 

A DIVISION OF COLUMBIA BROADCASTING SYSTEM, INC. 



6 



Show her the CBS carton with the 

Good Housekeeping Guaranty Seal. 
See Garry Moore sell your expert service 
over the CBS Television Net work. 

RADIO-ELECTRONICS 



www.americanradiohistorv.com 




TENS OF THOUSANDS 

OF ELECTRONICS TECHNICIANS NEEDED BY INDUSTRY! 

Let Ridet Books leach You Bleetnnics Know-How! 




FUNDAMENTALS OF TRANSISTORS 

by Leonard Kruffmtn 

Explains the BIG thing in electronics, today — 
the transistor J Written by one of the pioneers in 
transistor development, this book tells you all 
you need to know about this electronic miracle : 
basic operation, characteristics, performance, and 
application. Soft Cover, 144 pp., 5% x 8%". illus. 
#160 ...Only 12.70 

ENCYCLOPEDIA ON CATHODE-RAY 
OSCILLOSCOPES & THEIR USES 

by Rider A UsUn 

Fully and clearly describes the oscilloscope, ita 

construction and capabilities. Covert a wide 

variety of scopes, including: present day models. 

Profusely (3,000) illustrated. Cloth Bound, 1008 

pp., 8% x in rt , 

#133 Qnly $11.50 



TELEVISION— HOW IT WORKS 
(2nd Edition) 

by J. Richard Johnson 



A completely rewritten, up-to-the-minute edition 
of an authoritative and informative book. It is 
the newest and most comprehensive text on the 
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#101.. Only $4.60 

COLOR TELEVISION RECEIVER PRACTICES 

by Haieltine Corp. Lab. Staff 
Prepared by experts, this book covers every major 
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Soft Cover, 208 pp., 5% x 8%", illus. 
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RA0I0 OPERATOR'S LICENSE Q & A MANUAL 

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by M. Kaufman 

Revised and enlarged 5th edition contains the 
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766 pp.. 6% x B%", illus. 

#130 Only $6.60 



OBTAINING & INTERPRETING TEST SCOPE 
TRACES 

by John F. Rider 

Explains oscilloscope screen traces in clear, non- 
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190 pp., 6% x 8%\ illus. 

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INTRODUCTION TO COLOR TV 

(2nd Edition) 




by Kaufman & Thomas 



A revised, up-to-date edition of a best seller in 
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introduction to color television available. Soft 
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FM TRANSMISSION & RECEPTION 

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by Rider & Uslan 

Covers FM broadcasting of all kinds, and explains 
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Cloth Bound, 460 pp., &% x 8%". illus. 
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UNDERSTANDING VECTORS & PHASE 

by Rider & Uslan 

A book which makes for quick and easy under- 
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#103 , , Only $ .99 

BASIC VACUUM TUBES ft THEIR USES 

by Rider & Jacobowitz 

BaBic information relating to vacuum tubes, with 
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students. 208 pp., 6^ * 8%", illus. 

#171, Soft Cover * ...Only $3.00 

#171-H. Cloth Bound Only $4.50 

HOW TO TR0UBLESH00T A TV RECEIVER 

by J. Richard Johnson 

A book written for the newcomer, to aid in a 
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The "Clmie" in hi-fi llteHtm 

HI-FI LOUDSPEAKERS and ENCLOSURES by Abraham B. Cohen 



Really an education ... A book which 
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The book is supremely authoritative 
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Includes 18 blueprints of enclosures for 
home construction. 



368 pages 5% x %W Leather Finish MARCO Cover $4.60 





BASIC ELECTRICITY 
BASIC ELECTRONICS 
BASIC SYNCHROS & SERVOMECHANISMS 

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HOW TO USE TEST PROBES 

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Ideal budget all- 
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28 



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29 



www.americanradiohistorv.com 



Physicist G. K. Farney checks the frequency of Bell*s new klystron, which is located at far right. Tube's output is about 20 milliwatts. 



Sixty billion vibrations per second 



A great new giant of communica- 
tions—a waveguide system for carry- 
ing hundreds of thousands of voices 
at once, as well as television programs 
—is being investigated at Bell Tele- 
phone Laboratories. 

Such a revolutionary system calls 
for frequencies much higher than any 
now used in communications. These 
are provided by a reflex klystron tube 
that oscillates at 60,000 megacycles, 
and produces waves only 5 mm. long. 

The resonant cavity that determines 
the frequency is smaller than a pin- 
head. The grid through which the 
energizing electron beam is projected 
is only seven times as wide as a human 
hair, and the grid "wires" are of tung- 



sten ribbon 3/10,000 inch in width. 

G. K. Farney, University of Ken- 
tucky Ph. D. in nuclear physics, is 
one of the men who successfully ex- 
ecuted the development of the klys- 
tron. Dr. Farney is a member of a 




Grids in new tube, enlarged 30 times, with 
human hair for comparison. Electronic beam 
passes through smaller, then larger, grid. 



team of Bell scientists whose exciting 
goal is to harness the immense band 
widlh that is available with milli 
meter waves . . . and to make certain 
that your telephone system remains 
the test in the world. 




Wavelengths produced by the klystron tube 
are only .2 inch long— 1/15 that of the 
transcontinental radio relay system. 



BELL TELEPHONE LABORATORIES 

WORLD CENTER OF COMMUNICATIONS RESEARCH 




30 



RADIO-ELECTRONICS 



www.americanradiohistorv.com 




NEW! COLOR and Black-&- White 
LAB & TV 5" OSCILLOSCOPE #460 
KIT $79.95. Wired $129.50 

The FINEST professional 5 mc wide-band scope 
value. Ideal for research, h-f & complex waves, 
plus Color & Monochrome TV servicing. Flat from 
DC to 3.58 mc ±1 db (color burst freq.), flat DC 
to 4.5 mc +1, -3 db. Vert. sens. 25 rms mv/in. 
Vert. Z 3 megs. Has the following outstanding fea- 
tures not found in scopes up to several times its 
price, kit or wired: 

VERTICAL AMPLIFIER: direct-coupled (DC) 
thruout to eliminate 1-f phase shift; push-pull 
thruout for negligible distortion; K. follower coup- 
ling between push-pull pentode stages for extended 
h-f resp. (minimizes h-f phase shift, extends use- 
ful resp. to 10 mc); full-screen undistorted vert, 
defl; 4-step freq-compensated decade step attenu- 
ator up to 1000:1. SWEEP CIRCUIT : perfectly 
linear sweeps, 10 cps — 100 kc (ext. cap. for down 
to I cps); pre-set TV vert. & hor. positions (30 & 

7875 cps); automatic sync. ampl. & limiter elim- 
inates sync amplitude adj. PLUS: direct or cap. 
coupling; bal. or unbal. inputs; edge- lit engraved 
lucite graph screen; dimmer; anti-glare filter; 
bezel fits std photo equipt. OTHER IMPORTANT 
FEATURES: High intensity trace CRT. Finest sq. 
wave resp. (.06 usee rise time). Push-pull hor. 
ampl., flat to 400 kc, sens. 0.6 rms mv/in. Built-in 
voltage calibration. Intensity mod. Sawtooth & 60 
cps outputs. Astigmatism control. Retrace blank- 
ing. Instant, drift-free full-screen vert, positioning & 2X full-screen hor. 
positioning. Bal., cal.» astig. adj. externally accessible. 5UP1 CRT, 
2-6AU8, 2-6CB6, 1-12AU7A, 2-6J6, 1-6AX5, 1-1 V2. Deep-etched satin 
aluminum panel, rugged grey wrinkle steel cabinet. Designed for easy 
building at home with no special equipment. 13" x 8 Hi" x 16". 30 lbs. 
SCOPE DIRECT PROBE* #PD: KIT §2.75. Wired $3.95. Eliminates stray- 
pick -up & signal re-radiation. 

SCOPE DEMODULATOR PROBE* #PSD: KIT $3.75. Wired $5.75. Demodu- 
lates AM carriers between 150 kc and 250 mc 

SCOPE LOW CAPACITY PROBE* #PLC: KIT $3.75. Wired $5.75. For signal 
tracing in high frequency, high impedance & wide-band circuits (as in TV; 
without distortion from overloading or frequency discrimination. 




for COLOR and Monochrome TV servicing 

New! PEAK-to-PEAK VTVM #232 

& UNI-PROBE (pat pend,) 

KIT $29.95. Wired $49.95 



150 kc to 435 mc 
with ONE generator! 
Hew! RF SIGNAL GENERATOR #324 
KIT $26.95. Wired $39.95 

for COLOR and Monochrome TV servicing 

New wide-range, stable generator — better value then genera- 
tors selling at 2 or 3 times its cost! Ideal for: IF-RF alignment, 
signal tracing & trouble -shooting of TV, FM & AM sets; mar- 
ker gen.; 400 cps audio testing; lab. work. 6 fund, ran ges: 
150-400 kc, 400-1200 kc, 1.2-3.5 mc, 3.5-11 mc. 11-37 mc, 
37-145 mc; 1 harmonic band 111-435 mc. Freq. accurate to 

±1.5%; 6:1 vernier tuning 8c excellent spread at most import- 
ant alignment freqs. Etched tuning dial, plexiglass windows, 
edge-lit hairlines. Colpitts RF osc, directly plate-modulated 
by K-follower for improved mod. Variable depth of int. mod. 
0-50% by 400 cps Colpitts osc. Variable gain ext. mod. ampli- 
fier: only 3.0 volts needed for 30% mod. Turret-mounted 
coils slug- tuned for max. accuracy. Fine & Coarse (3-step) RF 
attenuators. RF output 100,000 uv; AF sine wave output to 
10 volts. 50-ohm output Z. 5- way jack-top binding posts for 
AF in /out; coaxial connector & shielded cable for RF out. 
Tubes: 12AU7, 12AV7, selenium rectifier; xfmr -opera ted. 
Deep-etched satin aluminum panel, rugged grey wrinkle steel 
cabinet. 8" x 10" x AV\". 10 lbs. 



The specs are the proof. . . 




ultbratici 
* without 
removing 
from cabinet. 



UNI-PROBE: exclusive with EICO!* Terrific 
time-saver! Only 1 probe performs all func- 
tions—a half-turn of probe-tip selects DC or 
AC-Ohms. 

The new leader in professional peak -to -peak VTVMs 
Latest circuitry, high sensitivity & precision, wide 
ranges & versatility. Calibration without removing 
from cabinet. New balanced bridge circuit. High Z 
input for negligible loading. 4 l /2" meter, can't-burn- 
Olit Circuit. 7 non-skip ranges on every function. 4 
functions: -f DC Volts, -DC Volts, AC Volts, Ohms. 
Uniform 3 to 1 scale ratio for extreme wide- 
range accuracy. Zero center. One zcro-adj. for all 
functions & ranges. 1% precision ceramic multi- 
plier resistors. Measure directly peak-to-peak 
voltage of complex & sine waves: 0-4, 14, 42, 140, 
420, 1400, 4200. DC/RMS sine volts: 0-1.5, 5, 
15, 50, 150, 500, 1500 (up to 30,000 v. with HVP 
probe, & 250 mc with PRF probe). Ohms: 0.2 ohms to 1000 megs. 
12AU7, 6AL5, selenium rectifier; xfmr-operated. %W x 5" x 5". Deep- 
etched satin aluminum panel, rugged grey wrinkle steel cabinet. 7 lbs. 

(teWf DELUXE PEAK-to-PEAK VTVM #249 

with 7Vt" METER & UNI-PROBE (pat. pend.) 
KIT $39.95. Wired $59.95 

All the advanced & exclusive features of #232-PLUS the 
extra convenience and readability of its big 1W meter. Your 
ideal bench instrument. 

VTVM RF PROBES* #PRM 1 or PRF-25: 

KIT $3.75. Wired $4.95. Accuracy ±10%. Use with any 
or 25 megohm VTVM. 

VTVM HV PROBE #HVP-2: Wired $4.95. Complete 
with multiplier resistor. Measures up to 30 kv with 
any VTVM or 20,000 ohms /volt VOM. 



4 NEW BEST BUYS 




Difly EICO Probes have at) these 
features: fully shielded; rugged terming 
b«»»rH p«rt» mounting f shock- mounted 
floating construction; swivel-action; 
color-coding; easy parts accessibili « 





COMPLETE 

with Preamplifier, Eaualizer and Control Section 

Afe|y/20-WATT Ultra-Linear Williamson- 
type HIGH FIDELITY AMPLIFIER #HF20 
KIT $49.95. Wired $79.95 

A low* cost, complete-facility amplifier of the highest quality 
that sets a new standard of performance at the price, kit or 
wired. Every detail, down to the etched, brushed solid brass 
control plate, is of the fine quality EICO is famous for. 
Rated power output: 20 watts (34 w peak). IM distortion (60 
cps: 6 kc/4:l) at rated power: 1.3%. Mid-band harmonic 
distortion at rated power: 0.3%. Maximum harmonic distor- 
tion between 20 and 20.000 cps at 1 db under rated power: 
approx. 1%. Power response <20w): ±0.5 db 20-20,000 cps; 
±1.5 db 10-40.000 Cps. Frequency response 04w) : ±0.5 db 
13-35,000 cps; ±1.5 db 7-50,000 cps. 

5 feedback equalizations for LP's & 78's including RIAA. 
Variable turnover feedback tone controls do not affect volume 

6 permit large boosts orients at either end of audio spectrum 
with mid -freqs. unaffected. Loudness control & separate level 
set control on front panel. Low Z output to tape recorder. 
4 hi-level switched inputs; tuner, tv, tape, auxiliary (xtal/cer- 
amic phono or 2nd tuner); 2 low-level inputs for proper 
loading with all leading magnetic, FM & quality xtal cart- 
ridges. Hum bal. control. Extremely fine output transformer 
has interleaved windings, light coupling, careful balancing k 
grain-oriented steel. %W x 15" x 10". 24 lbs. 



These amazing EICO values are NOW IN STOCK 
at your nearest distributor. Examine them 
side-by-side with ANY competitor. You'll see 
for yourself why indeed EICO is your BEST BUY, 
Fill out coupon on reverse page. 



TURN PAGE FOR MORE EICO VALUES.. 



Wither? Street, Brooklyn 11, New York 



MAY, 1956 



31 



www.americanradiohistorv.com 



Do you OVERPAY 
for QUALITY 
instruments? 



1956 



EICO's mass purchasing 
and world-wide distribution, 
together with advanced elec- 
tronic design, produce values 
never before possible ... to 
give you Laboratory Precision 
at Lowest Cost! 

GET the MOST for YOUR 
MONEY! Don't buy ANY 
test instrument till you put 
the EICO INSTRUMENT 
(kit or wired) equivalent be- 
fore you— and . . . 

Compare advanced elec- 
tronic design : see the latest in 
circuitry and features. 

Compare finest components : 
see the famous brands you 
know and trust, such as GE, 
Central ab, Mallory, etc. 

Notice ease of construction 
and operation: Exclusive " Be- 
ginner-Tested " Manuals make 
assembly and operation step- 
by-step, quick, crystal-clear. 
"You build them in one eve- 
ning—they last a lifetime !" 

Check 5 - Way Guarantee : 
Only EICO gives you this ex- 
clusive complete protection! 
EICO guarantees components, 
instructions and satisfactory 
operation — AND guarantees 
service and calibration for the 
LIFETIME of the instrument, 
at less than cost of handling. 

Compare feature for fea- 
ture, dollar for dollar. 

There's an EICO distribu- 
tor right nearby in your own 
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coast-to-coast. EICO planned 
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FORE YOU PUT DOWN ONE 
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COMPARE any of EICO's 
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Over 500,000 EICO instru- 
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EICO gives you LABORA- 
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1 EST COST, 





EICO CATALOG! 

Tells you how to SAVE 50% on 
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Pix Tube Test Adapter $4.50 



TUBE TESTER 

#625 

KIT $34.95 
Wired $49-95 

• tests 600 
mil series 
string type 

tubes 

• illuminated 
roll-chart 




VACUUM TUBE 
VOLTMETER #221 

KIT $25.95 
Wired $39.95 
• 

DELUXE VTVM 
ft 214 (7V 2 " METER) 

KIT $34.95 
Wired $54.95 




#944 FLYBACK 
TRANSFORMER & 
YOKE TESTER 
KIT $23.95 
Wired $34.95 

• fast check all 
flybacks & yokes 
in or out of set 

• spots even 1 
shorted turn! 




ft 12V BATTERY ELIMINATOR & 
CHARGER #1050 




New? BATTERY 
TESTER #584 
KIT $9.95 
Wired $12.95 



Tests A & B port' 
abte radio, hearing- 
aid, lantern, other 
batteries— in or out 
of equipment. 



Newl GEIGER COUNTER #803 
KIT $ J 9. 95 ^ired $29.95 

battel ies)^^^^^^f^^ 

Professional, all-electronic, sensitive 
rugged-at lowest cost! Indicates by 
neon lamp & headphone clicks. 




RF SIGNAL 
GENERATOR 

#320 
KIT $19.95 
Wired $29.95 
150 kc-34 mc, 
calibrated har- 
monics to 102 
mc. Pure or 
mod. RF, & 
Colpitts osc. 
400 cps sine 
outputs. 



Range 500 kc- 
228 mc on fund. 
Cont. sweep 
width control, 
0-30 mc. 

KIT $34.95 
Wired $49.95 



TV/FM SWEEP GENERATOR #360 
5MC-4.5MC CRYSTAL $3.95 ea. 




Sep. hi-gain RF 
& lo-gain audio 

inputs. 
Special noise 
locator. Calibra- 
ted wattmeter. 

KIT $24.95 
Wired $39.95 



DELUXE MULTI-SIGNAL TRACER #147 





5" PUSH-PULL 
•SC1LL0SC0PC 

#425 
KIT $44.95 
Wired $79.95 

7" PUSH-PULL 
OSCILLOSCOPE 
#470 
KIT $79.95 
Wired $129.50 



CATHODE RAY TUBE CHECKER #630 
KIT Si 7.95 Wired $24.95 




Easy, fast test of all 
types & sizes TV pix & 
scope CR tubes, in set 
or carton. 




1% accuracy on 
all 7 ranges. 
Range 75 kc- 
150 mc. 
Volt reg. 

KIT $39.95 
Wired $59.95 



0ELUXE RF SIGNAL GENERATOR #315 




20,000 Ohms/Volt 
MULTIMETER #565 

KIT $24.95 
Wired $29.95 



1000 Ohms/Volt 
MULTIMETER 
# 536 



KIT $12.90 
Wired $14.90 



9. • 

R-C BRIDGE 





Reads 0.5 ohms 




-500 megs, 10 




mmfd-5000 mf$ 




power factor. 


<? 


KIT 




$19.95 




Wired 


9 


$29.95 



& R-C-L COMPARATOR 
#950B 



VTVM PROBES KIT Wired 

Peak-to-Peak $4.95 $6.95 

RF $3.75 $4.95 

High Voltage Probe-1 $6.95 

High Voltage Probe-2 , $4.95 

SCOPE PROBES 

Demodulator $3.75 $5.75 

Direct $2.75 $3.95 

Low Capacity $3.75 $5.75 



for f*Ef 1956 catalog, mail coupon NOW! 



EICO 



| EICO, 84 Withers Street C-5 
| Brooklyn 11, New York | 

I Send FREE 1956 Catalog crnd nomt of neighborhood I 
| EICO jobber. | 

I 

|vHome Address | 

Prices 5% higher on West coast ©55 I City Zone Stote I 

and subject to change without notice. I ^ I 

■ Occupolion „ " 



Name 



84 Withers St. • Brooklyn 11, N. Y. 



Turn page for other f/co ad 1945 to j 955.3 decade of Know-How & Value Leadership in Kits & Instruments-over V2 million sold to date! 



32 



RADIO-ELECTRONICS 



www.americanradiohistorv.com 



It AIIIO - 

EIJ-CTIIOSSICS 

Hugo Gernsback, Editor 



THE ELEMENTS OF TELEDUCATION 

. , , The threat to our future can he /net . . . 



THE economy of the United States now rests squarely 
upon technical progress. For decades our know-how 
was second to none in all technical endeavors. We are 
no longer in this fortunate position. Indeed, we are 
now running in second place, having already surrendered 
our rank to the Soviet Union. In the graduation of tech- 
nicians and engineers, particularly in electronics, we are 
threatened with a further decisive setback. Not only is our 
economy thus threatened seriously, but our defense and our 
very existence are challenged. 

Unfortunately we cannot now quickly reverse this dis- 
astrous trend by supplying the nation with nonexistent 
and competent teachers, the supply of which is constantly 
shrinking. Only one other means is left open to us to 
ameliorate the condition — technical education via television 
— tcleduccttion. The present teacher shortage need not be 
an insurmountable obstacle. We have sufficient good teachers 
to reverse the downward trend in a few short years. 

The writer has spoken of this situation often * and fetls 
it necessary, due to the present emergency, to bring it up 
once more. Here is the plan briefly outlined: 

1. Russia has now definitely overtaken the United States 
in teaching and graduating of future technicians. They turn 
out far more vital technicians than we do. 

2. We have a disastrously low supply of technically com- 
petent teachers, who, due to inadequate pay, constantly 
defect to higher salaried industrial or other positions. 

3. The number of technical students has declined con- 
stantly and will continue to until our shortsighted teaching 
methods are reversed. 

4. Paradoxically, we have more good teachers than we 
actually need IF we only will use their talents intelligently 
to fit present-day technical growth. Why use an outstanding 
teacher to teach 100 students in a single institution IF THE 
SAME TEACHER CAN INSTRUCT 500,000 OR MORE 
SIMULTANEOUSLY? 

5. We HAVE the technical facilities today to achieve 
this via closed-circuit television. 

6. In short, without going into details, this is the way 
the proposed system, outlined by the writer in 1945, works: 
From a central point or points the best technical and science 
teachers in the land instruct via large wall projection color 
television ALL the classes in the land. If the instructor of 
the moment is at Yale, the rest of the country is connected 
to that point. The next lecture may come from MIT in 
Massachusetts, from Caltech in California or from any other 
point because all institutions of learning are tied in to the 
national teleducation closed-circuit hookup. Such lectures 
will not be merely talk. The teacher — be he a physics, chem- 
ical, electrical or electronics professor — will instruct directly 
from the laboratory all important experiments and make 
clear any technical point by actual physical demonstration. 

7. Technicians and engineers, however, are not created 
overnight. We must implant the seed of scientific adventure 
into the very young mind — before age 10. Country-wide 
teleducation MUST start in grade schools and be followed 
up with more intensity in high school. 

*Tfime. December 1945: Newxpeek, December. 1950; Radio-Ei.ectkoniCs, 
September, 11)51. Also Tec-Tele*lucation, Forecast, December, 1954, and 
K aimO-Electkonics, February, 1955. 

MAY, 1956 



8. During the present educational emergency, only the 
Federal Government has the means to finance a National 
Teleducation Network. The Government would build the 
network just as it has built roads in the past, the cost to 
be pro-rated to the states over a span of years. The Govern- 
ment would NOT be in the teaching business, however, and 
would have no voice in any educational program. To guard 
against abuse, the teleducational closed-circuit network 
could be supervised through a special commission or simi- 
lar agency. 

9. Teleducation via the national closed-circuit network 
does NOT do away with the teacher in the classroom- — 
supervision will still be needed. But why waste an Einstein 
type of educator on a 50-pupil class when a secondary 
teacher or qualified supervisor can do the paper work and 
all other necessary classroom routine? 

The writer is fully aware that such a revolutionary teach- 
ing system will meet some resistance from orthodox peda- 
gogues as well as the heads of many of our institutions of 
learning. Communications to us relating to universal 
country-wide teleducation seem roughly equally divided for 
and against. We have space for only two here: 

"I was very much interested in reading your article 
'Tec-Teleducation.' We are at the present time teaching 
a large class located in three different rooms by tele- 
vision. We have gone one more step by teaching by 
discussion method. We have a talk-back system so that 
students remote from the studio can ask questions 
and enter into discussion. This is at present an experi- 
ment and we have selected a course that we feel is 
most challenging to this type of teaching, Comparative 
European Government. 

"I doubt if our nontechnical people can see as far 
into the future of this thing as the technical people 
can. Our educators are usually too complacent once 
they have made a small gain. They are not inclined to 
expand the scope of what they have accomplished. 

"C. D. Phillips 
"Tech nical Su per vis or 
"State University of Iowa" 
* * * 

"Thank you for sending me a copy of the letter you 
received recently from Mr. Phillips of the State Uni- 
versity of Iowa. Certainly the arrangement he describes 
is a very interesting one. Such an arrangement is, I 
fear, a luxury in which only an institution supported 
by public funds can indulge. 

"However, as I indicated to you last week, our plans 
for the future include the development of a lecture hall 
designed for the use of television, and we look forward 
to an oppoi'tunity to experiment with this valuable 
adjunct to established educational methods. 
"Hakold Torgersen 
"Assistant D*an, College of Engineering 
"New York University" 

10. As the safety of the nation depends more and more 
on advanced technicians, engineers and scientists, such men 
should not be drafted for military service, but should be 
placed only in technical defense work. — H. G. 

33 



www.americanradiohistorv.com 



TEST INSTRUMENTS 



TRANSISTORIZING THE DIP METER 



Compact junction device 
tunes from 2.5—11 mc 

By T. QUEEN 

Editorial Associate 




Above — Meter is external to instrument. 
Left — Internal view shows parts layout. 



A GRID-DIP meter is, generally, a 
X\ tube oscillator with a meter to 
M \ measure grid current. When the 
dip meter is coupled to a near- 
by tank coil or other resonant circuit, 
energy is absorbed by the coil. As a 
result, there is a dip in the reading of 
the dip meter. When the meter is tuned 
for maximum dip, the external and dip 
circuits are in resonance. The unknown 
frequency of the tank may then be read 
on a calibrated scale on the grid-dip 
meter. The meter is also useful as a 
signal generator (it is essentially an 
oscillator), to check coil Q (by sharp- 
ness of dip tuning) and other related 
applications. 

To transistorize the dip meter it is 
important to consider the difference 
between a tube and a transistor. In a 
tube oscillator the grid acts as a diode 
to rectify the rf oscillations. There- 
fore, it is easy to measure the rf level 
with a meter in the grid circuit. It 
may seem that the same principle 
applies to a transistor . . . perhaps 
all we need is a meter in series with 
the collector (or other transistor ele- 
ment) . Unfortunately, this doesn't 
work. The reason is that each element 
of a transistor passes current at all 
times. Whether the transistor is oscil- 
lating or not, the current is essentially 
constant. For example, in a typical 
point-contact transistor oscillator, J 



measured 2 ma during oscillation; non- 
oscillating current was 1.6 ma. These 
may be called the 0 and N values, 
respectively. These values, therefore, 
vary only about 20%. Similar values 
hold for a junction transistor. In a 
typical circuit (Radio-Electronics, 
August, 1954, page 87) N is 650 pa, 
0 is 500 jua. 

In each case the N-0 difference is 
relatively small, representing at best 
a dip of about 20% on a meter scale. 
Yet this is not the whole story. This 
difference, small as it is, does not indi- 
cate the trite dip available during a 
measurement. No coil can be coupled 
so tightly that it will absorb all the 
energy from a grid -dip meter. Under 
normal conditions all we can expect is 
a dip of about 10-15% of the N-0 dif- 
ference. This comes out to only about 
2% of full scale as experiments have 
shown. For example, in a typical case, 
a coil was coupled 1 inch from the grid- 
dip meter. The dip was only one small 
division on the meter. Evidently the 
grid-dip principle cannot be used with 
transistors unless you want to use a 
magnifying glass, too. 

The problem may be solved easily. 
After attempting various complicated 
balancing and bucking networks, the 
following idea was adopted : A diode 
is added to rectify rf across the grid-dip 
meter tank and the current is fed to 
a dc meter. This approximates the oper- 
ation of a tube grid-dip meter! The 
diode rectifies just like a grid so we 



now have the entire meter scale to indi- 
cate oscillation level. With normal oscil- 
lation the meter is set to full scale. 
When oscillations cease (as from short- 
ing out the coil), the needle deflects 
back to zero. 

Now the N-0 difference is the whole 
meter scale! In one test, a coil was 
coupled to the grid-dip meter at a 
distance of 1 inch. The dip amounted 
to about 15% of full scale (to which 
the meter had originally been set). 
With tighter coupling (about ^-inch 
separation) the dip was to mid-scale. 
These are healthy dips for which no 
apology need be offered to tube instru- 
ments. 

This principle has been applied to 
a junction-transistor grid-dip meter 
and results have been most successful. 
A two-band device was constructed and 
has been tested under many conditions; 
a separate plug-in coil is used for each 
band. One covers from 2.5-5.5 mc; the 
other from 5.0 to over 11 mc. These 
ranges were chosen because they repre- 
sent the most useful portion of the 
frequency spectrum. For example, there 
is full coverage and overlap for any 
experiments and tests in or near the 
40- and 80-meter bands. 

The oscillator (see diagram) is a 
Raytheon 2N114, a high-frequency 
type. It has a frequency cutoff of 20 
mc, one of the highest values avail- 
able. While this article concerns itself 
only with a coverage up to 11 mc, there 
is no reason why this cannot be extend- 



34 



RADIO-ELECTRONICS 



www.americanradiohistorv.com 



ed considerably higher if desired. 

The oscillator is tuned by C3 which 
shunts plug-in coil L2. Coil L2 is 
wound on an Amphenol polystyrene 
form % inch in diameter, IV2 inches 
long. This form has a base which is 
to be screwed down to a Bakelite strip 
(see photo) 2 inches by % inch. The 
strip is drilled for a pair of banana 
plugs so the coil may be removed. 
This device has no on-off switch. This 
is not an oversight! The instrument is 
automatically shut off when the coil 
is removed from the banana jacks since 
this opens the negative side of the 
battery (when the external meter is 
disconnected)-, No matter how often 
you use this dip meter, the battery will 
last many, many months for the drain 
is very low. 

Capacitor C3 is a special unit recently 
introduced to transistor experimenters. 
It is only 3/16 inch thick, IV2 inches 
square. Yet it is a 365-M/uf variable 
capacitor effective over a 180° rota- 
tion! The secret is that this unit has 
a mica, dielectric between the metal 
movable "plates." It is obtainable from 
Lafayette Radio Co. as part number 
MS-215. 

Regeneiation (and oscillation) is 
produced by C2 which connects the 
emitter and collector of the 2N114. The 
value of 100 wf was found just right 
for the two bands covered by this 
instrument. If you are experimenting 
with much higher or lower frequen- 
cies, try other values for this capacitor. 

Coil LI is a loopstick with the core 
entirely removed and all excess form 
cut off. Ceramic capacitor Cl shunts 
it. This value was chosen after many 
experiments to obtain a nearly con- 
stant output over each band. A higher 
or lower capacitance here may cause 
a droop in output at either the high 
or low end of each band. I suggest you 
try a variable for Cl at the start, then 
choose the optimum value. For con- 
venience, Cl was placed inside the 
loopstick and the capacitor leads were 
used for making connections. The coil 
leads are very thin and cannot offer 
much support for the coil. So wrap the 
coil leads around the capacitor leads 
and let the latter do the supporting. 

The transistor leads are not clipped 
(see photo) as is usually done. Instead 
of a transistor mounting block, a three- 
terminal strip is used. The screw ter- 
minals hold the transistor leads tightly. 
This is only a matter of preference — 
the usual five-pin subminiature socket 
may be used if desired. 

The rf across L2 is rectified by a 
crystal diode and filtered by a disc 
capacitor before being fed to the dc 
meter. Potentiometer Rl controls the 
current to the meter to obtain full-scale 
deflection or any reading close to it. 
Another unusual component, Rl, is a 
"dime-size" pot only $4 inch in diameter 
with a shaft only Va inch in diameter! 
This tiny part is also available from 
Lafayette, their part number VC-34. 

The meter is a 200-/ua instrument. 
You may use a more sensitive unit if 

MAY, 1956 



you wish by using a larger resistance 
at Rl to prevent overloading. On the 
high band, average current is about 
230 jua; on the low band it averages 
about 300 pa. As constructed here, the 
grid-dip meter does not have an inter- 
nal meter. Thus, you can use your 
meter for other applications and not tie 
it down. Useful as the dip meter is, 
few technicians or experimenters need 
it for more than a few hours a week 
at most. It does not seem practical to 
incorporate the meter into the dip 
instrument. 

To calibrate the scale, insert the 
high-frequency coil and place it near 
an all-wave receiver. You can increase 
pickup by connecting the antenna 
lead of the receiver to the dip- 
meter chassis. Tune the receiver to 
various frequencies: 5, 5.5, 6 me, etc. 
This will calibrate the high range up 
to about 11 mc or beyond. 

As a bright idea I attempted to wind 
the low-frequency coil so that its cal- 



Parts for the dip meter 

2—10,000-, I — 220,000-ohm, '/ 2 - w «Jtt resistors; I — 10,- 
000-ohm potentiometer (see text); I— 100, 1—220 
lilif; I— .001-, I— .005-, I— 02-tif disc capacitors; I — 
365-iiiif miniature tuning capacitor {see text); I — 
2NII4 transistor; I — IN34A crystal diode; 2— 1.5-volt 
penliqht cells; | — 0-200- tia dc meter; I— 3-terminal 
mounting strip; I— loopstick; 2— tuning coils, high 
and low frequency (see text); 2 — banana jacks; 2 — 
pin iacks; 2— Bakelite strips with banana plugs 
mounted; 2 — polystyrene coil forms, %-inch diam- 
eter, 1 1/ 2 inches long; I— cabinet, aluminum, ap- 
proximately 21/4 x 2'/ 4 x 4 inches. 




[O SEE TEXT I 



Schematic of the grid-dip meter. 

ibration would be exactly half that of 
the high-frequency unit. Perhaps I 
was only lucky but the result was 
sensational. One coil covers frequencies 
exactly half that of the other, so only 
one calibration is needed. Only at the 
very low end is there a discrepancy. 
For example, 11 mc on the high-fre- 
quency coil corresponds exactly (to 
within the width of a line) to 5.5 mc 
on the low-frequency coil. They match 
all the way down so that 6 mc on the 
high-frequency coil corresponds to 3 mc 
on the lower unit. However, 5 and 2.5 
mc do not quite come in at the same 
spot on the respective coils, so a special 
calibration is made at this point. 

Here are dimensions for the coils 
which produced the above calibrations: 
The low-frequency coil has 23 turns 
occupying about % inch ; the high- 
frequency coil has 8 turns closely 
spaced. Both are wound with No. 22 
enameled wire. To produce the desired 
correspondence between coil calibra- 



TEST INSTRUMENTS 

tions, separate or push turns together 
as required. 

Using the instrument 

To make a measurement, plug in the 
desired coil and also the external micro- 
ammeter. Adjust Rl for meter indica- 
tion near full scale. The reading should 
remain nearly constant over most of 
the dial, but there may be a slight drop- 
off at either end. As an example, using 
the high-frequency coil, the meter may 
be set to full scale (200 Ma) at 11 mc. 
There is a variation of only one or two 
small divisions all the way down to 
5 mc and below. 

Uniformity of scale indication is 
controlled to some extent by Cl and LI. 
The original reading (before looking 
for a dip) does not necessarily have to 
be full scale. However, this is a con- 
venient starting point and provides 
maximum sensitivity. 

Having set the meter, couple the 
plug-in coil to the tank circuit under 
test. Either the grid-dip meter or the 
tank may be tuned for the dip. At first 
the coupling may be made very close, 
perhaps a V 2 inch or closer. Coupling 
may be reduced once a dip is detected. 

When coupling is fairly close, it is 
better to tune the dip-meter dial from 
the low-frequency end. Otherwise the 
changes in meter reading may be 
jumpy. With relatively weak coupling, 
it is better to approach resonance from 
the high-frequency end of the dial. 
Remember that highest accuracy re- 
sults from weak coupling. Often a dip 
may be observed with as much as a 
2-inch separation between dip-meter 
and tank circuit. 

The dip principle described may be 
used with any transistor oscillator. 
The 2N114 was chosen because of its 
extraordinary high-frequency cutoff. 
This particular unit will oscillate at 
even higher frequencies than the 11 -mc 
limit of the present unit. The battery 
voltage should be increased to (> volts 
for this purpose. Also, experiment with 
C2, Cl and LI for optimum results at 
very high frequencies. Note that the 
power input to the transistor is largely 
determined by the base resistor. 

This dip meter is also very satis- 
factory for use as a calibrated signal 
generator. Besides, it provides infor- 
mation for estimating circuit Q. If the 
dip is broad, the tank being tested has 
low Q. 

The dip meter is housed in an alu- 
minum Flexi-mount case, 2^x2^4x4 
inches. The two penlight cells which 
power it are mounted in a battery 
holder, available from Lafayette, Four 
jacks are mounted on the front end of 
the box. Two are banana jacks for 
the plug-in coil. The others are pin 
jacks for the external meter. When 
coil and meter are removed, we have 
a very compact instrument. By the 
way, remember to remove these units 
before storing the dip meter. When 
you do, you automatically open the 
battery circuit. end 

35 



www.americanradiohistorv.com 



TEST INSTRUMENTS 



Simplified TV 

ALIGNMENT 




Weston model 985 
v.h.f. calibrator. 

SERVICE technicians often shy 
away from realigning or check- 
ing alignment of TV receiver 
circuits because they are not suf- 
ficiently familiar with their equipment 
and alignment procedures or feel that 
the improvement in performance will 
probably not be great enough to com- 
pensate for the time required to set 
up the equipment. 

Fig. 1 shows a typical setup for 
realigning a TV receiver with a scope 
and sweep and marker generators. But 
it does not show the maze of leads 
draped across the chassis and bench 
or the spurious responses caused by 
improper grounds, stray coupling and 
out-of-tolerance components. Nor does 
it provide a remedy for the headaches 
that result when the marker signal is 
so strong that the set oscillates or when 
the marker pip disappears along the 
base line or close to an important trap 
frequency. 

Fig. 2 shows a simplified alignment 
setup recommended by Weston for use 
with their new model 984 sweep gen- 
erator and model 985 TV calibrator. 
This setup minimizes overloading in 
the TV receiver and provides a plainly 
visible marker at all times — even when 
set exactly at an important trap fre- 
quency. 

The r.f. circuits of the 984 sweep 
generator are conventional. A portion 
of the r.f. or i.f. output signal is tapped 
off and fed to the marker generator 
(model 985 TV calibrator) where it is 
mixed with the calibrator signal to 
develop a pulse type marker. This 
pulse is shaped, clamped and fed to 
the Z-axis input of the scope to mod- 
ulate the scope trace. The marker 



TV CALIB 
ORF OUT 



TV SWEEP GEN 
-©SCOPE 



OUTPUT 
O 



SCOPE ^ 



— J©CKT 



OUTPUT 
CKT o- 



IN H IN- 
0*~GNIL^O 



a 



Fig. 1 — Typical TV alignment setup. 
36 



Unusual v.h.f. 
calibrator provides 
accurate, easy-to-read 
markers 

By ROBERT F. SCOTT 

TECHNICAL EDITOR 



(Fig. 3) then appears as a double spot 
or a double hole in the response pat- 
tern, depending on whether the cali- 
brator's function switch is set to blank 
or brighten the trace at the marker 
points. 

The display at a is a type likely to 
be obtained with conventional align- 
ment procedures and equipment. The 
marker in the center of the passband 
is too strong and causes distortion. 
Markers at vital trap frequencies are 
attenuated too much to be visible. 

The displays at b and c result when 
markers are injected into the scope's 
Z-axis circuit. Marker visibility is con- 
stant regardless of its position on the 
trace. With positive-intensity markers 
at b the marker frequencies are cen- 
tered between two close-spaced dots. 
When negative-intensity markers are 
used, marker frequencies are indicated 
by the short line centered between two 
blanked portions of the trace as at c. 

Model 985 calibrator 

The variable marker-frequency sig- 
nal is developed by a capacitance-tuned 
oscillator covering 4 to 110 and 160 to 
265 mc in 10 fundamental ranges. A 
drum type dial with an effective length 
of 8*4 feet provides easy-to-read fre- 
quency indications — including TV 
sound and video carrier settings. The 
dial drum is coupled to the range 
switch so only the scale in use is visible. 

Rectangular markers are placed at 
4.5-mc intervals (see photo) and round 
markers are 1.5 mc apart on each scale. 
These points correspond to harmonic 
frequencies of the built-in 4.5- and 
1.5-mc crystal oscillators. A neon lamp 
indicates zero beat between the vari- 



TV SWEEP GEN 
oSCOPE OUTo- 
©CND CAL 



MODEL 984 




INPUT CKT 

° OUTPUT CKT 0 " 



Fig. 2 — Simplified alignment setup. 



able-frequency oscillator and the har- 
monics of the 4.5- or 1.5-mc crystal 
oscillators. A mechanical scale-shift 
control permits the operator to move 
the drum laterally so the pointer lines 
up accurately with the crystal calibra- 
tion points. 

The crystal-controlled frequencies 
may be used to modulate the v.f.o. and 
provide additional markers on each 
side of the v.f.o. marker. The 985 can 
be used as a modulated or unmodulated 
crystal-controlled signal source for 
adjusting traps, aligning FM circuits, 
as a heterodyne type frequency meter 
for calibrating signal generators and 
small transmitters and identifying the 
frequency of unknown signals. It also 
provides bar patterns for linearity ad- 
justments. 

The circuit of the 985 is shown in 
Fig. 4. The v.f.o. signal developed by 
the 6T4 Colpitts oscillator is taken 
from the plate circuit and fed to the 
RF OUT terminal through a CK705 
crystal diode modulator and the r.f. 
attenuator. The diode permits the v.f.o. 
output to be amplitude-modulated by 
4.5 mc, 300 kc or 400 cycles. 

The function control is set to calib 
& HET for calibrating the v.f.o. against 
the built-in crystals or identifying un- 
known signals. A part of the signal 
from the 6T4 is fed to the cathode of 
the 6BA7 mixer. Throwing the CRYSTAL 
switch to 1.5 MC or 4.5 MC turns on 
the crystal oscillator (V2-a) and 
injects its signal into grid 3 of the 
6BA7. The v.f.o. and crystal oscillatoi 
signals heterodyne in the untuned 
mixer plate circuit that responds to 
low audio frequencies. This heterodyne 
signal is amplified by V2-b and fed to 
the 6CL6. A neon lamp beat indicator 
and 47,000-ohm resistor are in series 
across half of the tapped primary of 
output transformer Tl. When the dif- 
ference between the v.f.o. and crystal 
fundamental or harmonic is around 
1,000 cycles, the neon indicator lights. 
Exact zero beat is indicated when the 
light is sharply extinguished. 

To calibrate the v.f.o., the dial 
pointer is set to the calibration point 
nearest the desired frequency and the 
crystal oscillator is turned on with the 
crystal providing a harmonic at the 
calibration point. The tuning dial is 
then rocked about the calibration point 



CONVENTIONAL MARKERS 




MARKER TOO STRONG -DISTORTS RESPONSE 



NO DISTORTION 
+ 



#FAIR MARKER 
W MARKER NO MARKER 



NEG INTENS MARKERS 





MARKERS VISIBLE AT TRAP SETTINGS 
b 



note:- caub freq is at CENTER OF 2 DOTS 
Fig. 3 — TV receiver response patterns. 

RADIO-ELECTRONICS 



www.americanradiohistorv.com 



TEST INSTRUMENTS 



and carefully adjusted to the position 
where the indicator light goes out. If 
the pointer is not now exactly on the 
calibration point, the operator shifts 
the dial right or left until the pointer 
and calibration point coincide. Dial 
calibration accuracy is now the same 
as that of the crystal — .01%. 

A signal whose frequency is un- 
known is checked by feeding it into 
grid 1 of the 6BA7 mixer and tuning 
the v.f.o. until zero beat is indicated. 
The frequency of the unknown signal 
is the same as the dial reading. 

Marker circuit 

When the Z-axis circuit is operated, 
signals from the v.f.o., crystal os- 
cillator and sweep generator are fed 
to the 6BA7 mixer where they produce 
a large number of beat frequencies. 
The mixer plate load is now a 75-kc 
tuned circuit. The swept signal starts 
at a low frequency and rises to a 
frequency above that of the v.f.o. in 
the calibrator. A voltage is developed 
across LI - C4 in the mixer plate cir- 



cuit when the sweep frequency is 75 
kc below the v.f.o. and again when it 
is 75 kc above. This 75-kc signal is 
amplified by V2-b and then rectified by 
one of two CK705 germanium diodes 
to produce either a positive or negative 
pulse. 

This pulse is amplified in the 6CL6, 
clamped by the 6AL5 and then fed to 
the z-axis OUT terminal where it is 
taken off and used to brighten or blank 
the scope trace. (See Fig. 3.) When 
positive-intensity marking (trace 
brightening) is used, the calibrator 
frequency is midway between the two 
bright spots. W T ith negative-intensity 
marking (blanking) the 75-kc points 
are marked by narrow gaps on each 
side of the calibrator frequency. 

When the crystal oscillator is turned 
on, its signal is fed into the mixer and 
appears as sidebands on the v.f.o. 
signal. As the sweep signal passes over 
these sidebands additional markers are 
produced simultaneously at the side- 
band frequencies. For example, if the 
v.f.o. is set to a picture r.f. or i.f. 



carrier frequency and the 4.5-mc crys- 
tal is switched on, a second marker 
will appear 4.5 mc away at the sound 
carrier frequency. The other 4.5-mc 
sideband will normally be outside the 
passband of the receiver's circuits and 
will not produce a marker on the scope 
pattern. When the 1.5-mc crystal is 
used, several markers will appear 1.5 
mc apart on the pattern. 

Offset markers 

W T hen a set is far out of alignment 
or interstage shielding is poor, os- 
cillations may occur when a marker 
signal is applied. In this case, oscilla- 
tions or overloading caused by strong 
markers can be eliminated by setting 
the v.f.o. to a frequency 4.5, 9, 13.5 
or 18 mc above or below the desired 
frequency and switching on the 4.5- 
mc oscillator. The sidebands of the 
v.f.o. will then fall exactly on the 
desired marker point. Thus, by using 
successively higher sidebands it is pos- 
sible to attenuate the marker to the 
desired degree. end 



cmod 




i 1 



Fig. 4 — Schematic of the Weston model 
985 v.h.f. calibrator. Instrument per- 
mits simplified alignment procedure. 



MAY, 1956 



www.americanradiohistorv.com 



TEST INSTRUMENTS 




Unit permits checking 
chroma circuits with a 
narrow-hand scope 



CHROMA PROBE 



MOST oscilloscopes used in serv- 
ice shops are of the narrow- 
band type and cannot do a 
thorough job of color TV serv- 
icing. The probe described in this article 
(see photos) is made for just such 
scopes and permits viewing the chro- 
minance portion of a color TV signal; 
it can be used to measure burst ampli- 
tude or chroma. 

The probe (Fig. 1) consists of a high- 
pass filter which removes the color 
information from the composite signal 
and passes this on to a 3.58-mc trap. 
The subcarrier trap is broad enough 
to pass the color information sidebands, 
approximately plus and minus 500 kc. 
This band of frequencies is then rec- 
tified and filtered in a low-pass network 
so as to apply only the low-frequency 
component to the scope. 

The output of the chroma probe is 
proportional to the chrominance ampli- 
tude and is not affected by the lumi- 
nance component. Its input impedance 
is high enough so that the probe can 
be used across the low plate and cathode 
resistors found in most video amplifiers 
without introducing distortion. 

Construction and adjustment 

The chroma probe layout is shown in 
Fig. 2. The %-inch brass end piece is 
drilled out to V 4 inch for the coaxial 
cable. The cable shield is soldered to 
a solder lug by drilling and tapping 
the end piece for a 4-40 screw and 
fastening the lug to the screw. 

The parts may then be assembled 
(except for the Bakelite end piece) as 



IN56 L? 



^PR09E SHELL 

Fig. 1 — Schematic of the chroma probe. 
38 



in the photo. Drill the Bakelite end 
piece for the probe tip made from a 
piece of brass rod 2 inches long and 
% inch in diameter. The rod should 
be threaded for a 6-32 screw with % 
inch of thread; it is held in place with 
two 6-32 nuts. 

Both end pieces are force-fit so no 
screws are necessary. With the parts 
completely assembled, drill a hole in 
the probe housing (see photo) so that 
C2 can be adjusted for tuning the 3.58- 
mc trap. 

Finally, the open end of Cl is sol- 
dered to the tip and the Bakelite end 
piece put into place. To keep parts 
from shorting after assembly, insert 
a sleeve of empire cloth or similar 
material inside the tubing. 

To tune the trap it will be necessary 
to use a television receiver tuned to a 
channel transmitting a color bar signal 
or program with a stripe signal. Place 
the probe at the output of the video 
detector. Set the scope sweep for 7,875 
cycles. Adjust the trap for maximum 
indication on the scope. It is a good 
practice when using this probe or when 
doing any video checking with a scope 
to synchronize the scope externa ly 
with a capacitance pickoflf from the 
yoke or flyback transformer. This can 
be done by clipping a lead from the 
scope external-sync binding post to a 
yoke lead. It is not necessary to punc- 
ture the yoke lead insulation. External 
synchronization allows the scope pat- 
tern to remain locked in regardless of 
amplitude or polarity of the signal 
being viewed. 



«• 32 Thread i/2" 



7 

1/8 BRASS ROD 

BAKELITE. 
END PIECE 



3/4* to brass Tubing 



1/4 TAP PED 
FOR 4-4C SCR 



.-J BRASS 
PIECE 



Fig. 2 — Mechanical layout of the probe. 




Probe complete with the coax connector. 

The scope ground must be connected 
to the chassis ground. 

Using the probe 

The probe can be used to measure 
the relative amount of chroma a re- 
ceiver will pass. It is not intended for 
use in rf or if alignment; this job is for 
a sweeper. After this is done the probe 
can be put at the output of the video 
detector to check for antenna mismatch, 
which can account for loss of color in- 
formation although the black-and-white 
picture may appear normal. 

The probe can be used at the output 
of the burst-gate tube to check for the 
presence of the color burst after keying. 
The output of the bandpass amplifier 
can be observed to check for proper op- 
eration of the color killer circuits. The 
final check point at which the probe 
may br used is at the grid of the I and 
Q or R — Y and B — Y demodulators. 
Beyond this point the video color in- 
formation has frequencies up to only 
500 kc, or 1500 kc in the case of the I 
channel, sp normal scope tracing may 
be used. 

A vtvm may be used to check the CW 
RADIO-ELECTRONICS 



www.americanradiohistorv.com 




operation of a receiver's local 3.58-mc 
oscillator up to the demodulator grids 
to complete the checking of the chroma 
portions of a color receiver. 

Fig. 3 shows the standard horizontal 
waveform of the NTSC color bar pat- 
tern. The colors are arranged in their 
descending order of luminance: white, 
yellow, cyan, green, magenta, red and 
blue. The relative amplitudes of chroma, 
as displayed by this probe, are not so 
regular. They are as follows: 

Yellow 69% Magenta 88% 
Cvan 94% Red 94% 
Green 88% Blue 68% 

The input pattern was taken at the 
output of a receiver video detector with 
a wide-band oscilloscope. The output 
picture was taken with the probe at the 
same point using a narrow-band scope. 

Fig. 4 was made under the same con- 
ditions. Most television stations trans- 
mitting color programs will insert a 
stripe signal on their black-and-white 
programs to aid in adjusting and check- 
ing color-receiver operation during in- 
stallations. The stripe signal consists of 
two bursts of 3.58 mc of approximately 
2 microseconds' duration just preceding 
the front porch and just following the 
back porch of the horizontal sync. The 



pig. 3 — Standard horizon- 
tal wa\eform of NTSC 
color bar pattern: above, 
video detector output as 
seen with wide-band oscil- 
loscope; below, the same 
output using the probe 
and narrow-band oscillo- 
scope. 



Fig. 4 — Color stripe sig- 
nal in monochrome trans- 
mission: above, with wide- 
band scope; below, with 
probe and narrow -band 
scope. 



stripe following the back porch locks in 
the receiver's 3.58-mc oscillator and 
the stripe preceding the front porch 
appears as a greenish yellow bar on the 
right edge of the color-television screen. 



TEST INSTRUMENTS 

A.C.-D.C. PROBE 

IF you do a lot of testing with a 
v.t.v.m., you probably have occasion 
to measure d.c. or a.c. voltages at 
about the same time. With separate 
d.c. and a.c. probes you will have to 
keep changing probes or group your 
d.c. and then your a.c. measurements. 

In a combined probe you simply in- 
clude both probe circuits within the 
same shielded cable. The common lead 
is the same for both. The hot a.c. lead 
includes an isolating capacitor (see 
diagram) and filter network. The cor- 
responding d.c. lead needs only the 
usual isolating resistor. The capacitor 
used was chosen because it fitted snugly. 

The probe is enclosed in a brass 
cylinder, 4% inches long and % inches 
in diameter. The business end is a 
needle prod set into a rounded piece 
of polystyrene. Poly cement is used 



Parts lis* for chroma probe 

I — 1,500-ohm resistor; I — 50-mif capacitor (Centra- 
lab TCN tubular ceramic or equivalent); I — 100-mif 
capacitor, silvered mica, 5%; I— 250-uuf capacitor, 
silvered mica, 5%; I — 5-50-mif, trimmer capacitor 
(Centralab 822-AN or equivalent); I— IN56; l—LI. 
50 turns of No. 26 wire wound in 2 layers on '/ a -inch 
Lucite rod over % inch, 15 \ih; I— L2, 40 turns of 
No. 26 wire wound in 2 layers on '/a-inch Lucite fod 
over 5 / 8 inch, 10 nh; I— 4-foot length RG59/U coaxial 
cable; I— connector or jack, depending on scope 
input connection; I— 4-inch length brass tubing, 
^4-inch inside diameter; I— brass end piece, 3,4-inch 
round stock, '/i-inch long; I— Bakelite end piece. 
3/i-inch round stock, "A inch lonq; I— 2-inch lenqth 
>/ 8 -inch brass rod threaded for 6-32. 'A inch, on one 
end. 



When the probe is used on a video 
signal containing a 3.58-mc stripe, the 
output will appear as two pips on either 
side of the video blanking interval. 
These pips can be used in tracing the 
color information just like a color-bar 
pattern. However, only the burst fol- 
lowing the horizontal sync pulse will 
appear at the output of the burst keyer 
and the burst preceding horizontal sync 
will appear in the bandpass amplifier 
channel. end 



NEEDLE 
POINT 



"outer brasscase 
"Imeg" 

I 

\% 




^SELECTED FROM IfrMEG 5X UNITS 



Materials for a.c -d.c. probe 

|_|_ I — 10, l— 15.5-meqohm, 1% resistors (the latter 
may be a selected 16-meqohm 5% unit or 15 meg- 
ohms and 500,000 ohms 1% in series); I— .001, I— 
.02-nf capacitor; 2— 4-prong cable type plug, I — 
4-prong cable type socket, I — 4-prong chasm type 
socket, brass sleeve, cable, clip as indicat ed in text. 




MAY, 



1956 



to hold the prod firmly in place. The 
other end of the probe is a four-pin 
miniature plug, of which only three pins 
are used. 

A three-conductor extension cable ties 
the probe to its v.t.v.m. This permits 
the probe to be detached from its cable 
so it may be kept safely in a desk 
drawer while the cable is hung up some- 
where. Also, it allows the cable to be 
used for other purposes. 

The far end of the cable is a male 
unit which plugs into a female socket 
on the front panel of the v.t.v.m. A 
toggle switch must be added on the 
voltmeter panel to switch from d.c. to 
a.c. as required, without need for 
changing probes. 

The component values shown in the 
schematic are for a v.t.v.m. with an 
input resistance of 10 megohms, a com- 
mon value. With these values, the 
meter calibration will be correct for 
both a.c. and d.c. — Nathaniel Rhita. 

39 



www.americanradiohistorv.com 



TEST INSTRUMENTS 





Inexpensive 
Capacitor 
Checker 



The Knight model F 119 
capacitor checker. 



The Knight in-circuit 
tester kit makes for 
rapid servicing 



By NORMAN KRAMER* 



CAPACITORS are made to a great 
many specifications. However, re- 
gardless of the manufacturing 
technique or the voltage— capaci- 
tance rating, there are two basic prop- 
erties all capacitors have in common — 
the ability to block dc and to pass ac. 

To determine the condition of a 
capacitor in a given circuit, with ordi- 
nary equipment, one lead must be un- 
soldered to isolate it from the rest of 
the circuit. This method is time-con- 
suming because many good capacitors 
may have to be unsoldered before the 
faulty one is found. Perhaps more im- 
portant, the trend in modern receivers 
and other electronic equipment is defi- 
nitely toward printed-circuit wiring. 
Here, with the short component termi- 
nals and the ever present danger to foil 
pattern, phenolic and bonding of the 
foil to the phenolic, unsoldering and 
resoldering capacitors can be costly. 
The new in-circuit capacitor checkers 

•Project Engineer, Allied Radio Corp., Chicago, III. 




~]TE5T CABLE 

l vm «LU asm 



C2 1 ,A\iH | 



T 



TEST CLIPS 



Fig. 1 — Diagram for open-circuit test, 
40 



permit service technicians to check 
capacitors quickly while they are still 
soldered into their associated circuits. 
The test leads from the instrument are 
placed across the capacitor and the test 
switch depressed. Observing the condi- 
tion of the tuning eye, one can deter- 
mine if the capacitor is open. Pressing 
another switch and again observing 
the condition of the eye provides a 
short test. Thus, both the open and 
short tests are made without disturbing 
the leads or the circuit. 

An example of this type of instru- 
ment is the recently released Knight 
capacitor checker kit. This instrument 
has tw r o separate test circuits to show 
whether capacitors are open or shorted. 

Fig. 1 is a simplified diagram of the 
open-circuit test. Hartley oscillator VI 
operates at a frequency of approx- 
imately 20 mc, with Ll-Cl forming 
the tuned circuit. Pickup coil L2 is 
close-coupled to the tank circuit and 
feeds network Zl, consisting of C2, L3 
and C3. This network and the 48-inch 
coaxial cable to the test clips make up 
a quarter-wave transmission line at 




TEST CLIPS 



Fig. 2 — Diagram for short-circuit test. 



approximately 20 mc. Without Zl. 
which serves as an artificial line, the 
test leads would have to be over 12 
feet in length to be a quarter wave- 
length at 20 mc. 

An interesting property of a quarter- 
wave line is that any impendance con- 
nected at the output is reflected to the 
sending end as a reciprocal. That is, if 
the output end is open, the input end 
"sees" a short circuit and vice versa. 
Thus, if the test clips are open or con- 
nected to an open capacitor, the sending 
end of L2 sees a short circuit, or zero 
voltage. The voltage across L2 is recti- 
fied by the diode and applied to the grid 
of V2, keeping the eye normally open. 

If L2 sees a short circuit (an open 
capacitor), no voltage is impressed on 
the grid and the eye remains open. 
If, however, a normal capacitor is con- 
nected across the test leads, a voltage 
appears across the test leads, is applied 
across L2, rectified and fed to the grid 
of the eye tube. This causes it to close 
in proportion to the magnitude of the 
voltage. A capacitor of 20 fifif will 
cause practically complete closing; any 
capacitance larger than this will def- 
initely close the eye. Capacitors smaller 
than 20 fifii will cause partial closing. 
Shunting resistances of 50 ohms or 
less across the capacitor under test will 
cause the eye to close, indicating a good 
capacitor even though the capacitor 
may be open. (A description of a similar 
circuit appeared in the July, 1954, issue 
on page 53. — Editor) 

Fig. 2 is a simplified schematic of 
the short-circuit test. With the test 

RADIO-ELECTRONICS 



www.americanradiohistorv.com 



TEST INSTRUMENTS 





Left — Rear view of the tester, showing the 6E5 
assembly and oscillator adjustment. Above 
— Underchassis view of capacitor checker. 



selector switch in this position, the 
heater winding of the transformer fur- 
nishes, through Rl and CI, a proper 
bias voltage which is impressed across 
R2, closing the 6E5 eye tube. The test 
clips in this test shunt R2. If the test 
clips are shorted, bias voltage is lost 
and the eye opens. Thus, any shorted 
capacitor will open the eye. Capacitors 
which are merely leaky will only shunt 
R2, reducing the bias voltage but not 
eliminating it. Actually, a leaky capac- 
itor must be almost completely shorted 
to open the eye completely. 

The bias voltage is chosen to make 
the test insensitive to high resistance. 
Therefore, good capacitors larger than 
2,000 fii whose reactance is extremely 
low, or good capacitors which are across 



resistors of less than approximately 
20 ohms, will show partial eye opening. 
The 7-45-«Mf ceramic trimmer capac- 



Parts for capacitor checker 

Resistors: 1—10,000, 1—47,000, 3—470,000 ohms, '/ 2 
watt, 10%; I — 47 ohms, I watt. 

Capacitors: 1—25, 1—200 ( 5%), 1—250 mica; 
I— .0015, I— 0.1 iif; I — 20-p.f electrolytic, 150 volts; 

1 — 7 — 45-ji^i.f trimmer. 

Coils: I— oscillator type (LI), 12 turns of No. 22 
enameled wire wound on a 5 / 8 -' nc n diameter coil 
form, tapped at 6 turns; 2 — coils (L2 and L3) 0.4 
\ih, 12 turns of No. 28 enameled wire closewound 
on '/ a -Inch diameter form. 

Miscellaneous: I — 50-ma selenium rectifier; I — I N5I 
crystal diode; 2 — spst slide switches; I— dpdt slide 
switch; I — transformer, 140 volts at 20 ma, 6 3 volts 
at I amp; I — &E5 and 6-pin socket; I— 6C4 and 
miniature 7-pin socket; I — mounting bracket for 
6E5; I— chassis; I — 48-inch length of coaxial cable; 

2 — alligator clips. 



itor is the only variable element in the 
entire circuit. So when the instrument 
is assembled and the coaxial test lead is 
left hanging free, a simple screwdriver 
adjustment will tune the oscillator to 
approximately 20 mc, making the test 
lead and the load line exactly a quarter 
wavelength long. 

Fig. 3 is a complete schematic of the 
Knight capacitor checker kit. The 
power supply consists of a half-wave 
rectifier using a single 20-/*f filter 
capacitor. Further filtering is unneces- 
sary as it will not affect operation. The 
6.3-volt secondary winding of the power 
transformer supplies the heater volt- 
ages and the bias voltage to the 6E5 
when the instrument is in the short- 
test position. Switch SI must be closed 
before each test is performed; S2 selects 
either the open- or short-circuit capaci- 
tor test. 

In some cases a short may be inter- 
mittent. Therefore, it is a good idea to 
tap or jar the capacitor under test and 
note any flicker of the indicator. By so 
doing a very troublesome intermittent 
short may be discovered. 

Shorted capacitors may be somewhat 
obvious, especially where they cause 
complete loss of tube voltages. Open 
capacitors may have a far more subtle 
effect and, hence, be more difficult to 
detect. Such capacitors could cause 
signal loss, serious change of wave- 
form or instability. 

In view of the time-saving features 
alone, an in-circuit capacitor checker 
can be a welcome addition to any 
service shop. END 

41 




www.americanradiohistorv.com 



TEST INSTRUMENTS 



Test unit permits rapid design 
of transistor circuitry 



the 

transigner 




A front view of 
the transigner.. 



Except for power sup- 
ply, all components 
are located under 
transigner chassis. 




42 



By FORREST H. FRANTZ, SR.* 

SINCE the appearance of the tran- 
sistor, considerable emphasis has 
been placed on the wide variations 
between transistors of a given 
type. This has been so well publicized 
that I was convinced that attempts at 
graphical and analytical amplifier de- 
sign would be futile. The prospect of 
having to change resistors in a minia- 
ture transistor amplifier was not at all 
pleasant. This wastes time, usually 
messes up the looks of an amplifier and 
occasionally leads to ruined parts. 

This little unit was created to over- 
come these difficulties. The transigner 
method of amplifier design is fast and 
accurate. Many experimenters do not 
like to become entangled with calcula- 
tions. For those, the big advantage in 
the transigner approach is that calcula- 
tions may be dispensed with, optimum 
operating values predicted and tran- 
sistors with abnormal characteristics 
may be easily detected. 

What is the transigner? It is simply a 
grounded-emitter amplifier circuit and 
variable power supply equipped with 
variable bias resistances. To change 
the operating voltage, you turn a 
potentiometer; to change the value of 
any resistance, you turn another (Fig. 
1). The dc voltage applied to the tran- 
sistor circuit may be varied with the 
7,500-ohm voltage divider in the power 
supply circuit. The collector bias resist- 
ance may be adjusted by varying the 
100,000- and 10,000-ohm potentiometers 
connected in series in the collector cir- 
cuit. A 10-megohm pot in the base cir- 
cuit controls base bias resistance and 
5,000- and 1,000-ohm units in series 
With the emitter permit varying the 
emitter bias resistance. With these 
controls you can design a transistor 
audio amplifier in minutes. 

The original transigner was a cheap 
and dirty arrangement constructed in 
3 hours. Stress was placed on ease of 
operation, versatility and ease of inter- 
pretation rather than elegance. The 
bottom view of the transigner reveals 
that a large number of blank tie-down 
points are available. These were pro- 
vided so that changes could easily be 
made in the circuit later if desired. The 
transistor socket and the terminal 
strips were fastened to the meter with 

* Physics Dept., Mississippi State College 

radio- Electronics 



www.americanradiohistorv.com 



Duco cement. The meter is not essential 
since a bench instrument may be used to 
adjust the applied dc voltage. 

The switch permits speedy measure- 
ment of input and output voltages and 
waveforms. The leads from an oscillo- 
scope and an audio vtvm clip to the 
ground bus and the center switch ter- 
minal. The signal leads from an audio 
generator connect to the input termin- 
als. The power transformer and several 
associated components are wired sep- 
arately to avoid hum pickup. They 
should be placed in an enclosure (I use 
a cardboard power-transformer box) 
for safety. The power supply in the 
transigner circuit was designed for 
p-n-p type transistors such as the Ray- 
theon CK722. For n-p-n transistors such 
as the 2N35, a negative ground is 
required and a conventional utility 
power supply can be used. 

The markings on the front panel may 
be made with India ink. They should be 
made prior to wiring, using an ohm- 
meter to determine calibration points. 
The builder who does not include a 
voltmeter in his transigner may cali- 
brate his dc voltage control with an 
external voltmeter and be assured of 
reasonable accuracy. 

Using the transigner 

To design a grounded-emitter tran- 
sistor amplifier stage, place the tran- 
sistor to be used in the socket (be sure 
to make proper connections). Connect 
an audio signal generator to the input 
of the transigner and an audio volt- 
meter and oscilloscope to the center 
switch terminal and ground. Set the 
resistance controls to approximately 
correct values. For example, if a 
CK722 is to be used with a 6-volt 
supply, set the base bias to 250,000 
ohms and the collector bias to 20,000 
ohms if a high-impedance output load 
is to be used. The approximate settings 
are not critical. The power may then 
be applied and the voltage control 
advanced to supply 6 volts. The base 
and collector bias controls are then 



-O TO tS VTVM 4 SC0P£ (WHEN USCD) 
OUT jf-O 




manipulated for maximum gain and 
best output waveform. 

Although the audio generator output 
control is kept at a constant setting, 
the input voltage to the amplifier may 
vary with changes in the transigner 
control settings. Therefore, to be sure 
about the gain of the amplifier stage, 
you must always divide the output 
audio voltage by the input audio volt- 
age. 

The emitter bias resistance plays an 
important role in grounded-emitter 
amplifiers. An unbypassed emitter bias 
resistance stabilizes the amplifier by 
minimizing shifts in the dc operating 
point with temperature changes. It also 
increases the input impedance of the 
amplifier. Since it is often desirable to 
cascade amplifier stages or use high- 
impedance input devices, the latter fea- 
ture is particularly important. A fur- 
ther effect of the emitter bias resistance 
is to improve low-frequency response. 
Of course, a price must be paid for 
these improvements and the cost is a 
reduction in amplifier gain. 



DC 



SUPPLY 



GROUNDED-EMITTER AMPLIFIER 

Input 



Dc 


1 


Rit Re 


Voltage 


Imped* 


volts 


fohmsJ 


fohmsJ (ohms) Goin 


once 


3 


10,000 


200,000 0 


59 


2,300 




500 


14.1 


9,300 


& 


10,000 


250,000 0 


112 


1,800 




500 


15 6 


10,400 






1,000 


8.6 


18,800 


22.5 


40.000 


900,000 0 


500 


1,260 






500 


64 


10.200 






1,000 


33.3 


19 200 



Fig. 1 — The transigner. All transistor 
voltages can be varied. 

MAY, 1956 



Fig. 2 — Diagram of test circuit and 
data obtained using ■ K722 transistor. 

Fig. 2 contains some experimental 
results for various circuit values for a 
grounded-emitter amplifier using a 
CK722 transistor. It indicates perform- 
ance with various circuit values. Note 
that for the particular transistor used 
for this data, an emitter bias resistance 
of 500 ohms increased the input impe- 
dance to approximately 10,000 ohms 
and a resistance of 1,000 ohms increased 
it to approximately 20,000 ohms. 

If the amplifier you're designing is 
to drive a load of less than 100,000 
ohms, the loadvhould be connected at 
the output terminals of the transigner. 
This is necessary because the output 
load has considerable influence on the 
operation of a transistor amplifier. For 
example, if you intend to use the ampli- 
fier stage you're designing to drive a 
second transistor amplifier stage, the 
second stage will present a load of 
approximately 1,500 ohms to the col- 
lector circuit of the first amplifier 
(assuming zero emitter bias resistance 
for the second stage). In such a case 



TEST INSTRUMENTS 

you should connect a 1,500-ohm resist- 
ance to the output of the transigner 
to simulate the actual load. If the sec- 
ond amplifier stage has an emitter bias 
resistance of approximately 1,000 ohms, 
the input impedance (and consequently 
the load on the first stage) will be 
approximately 20,000 ohms and a simi- 
lar resistor should be connected to the 
output of the transigner. 

You might say, "That's fine and 
dandy, but how can I find the input 
impedance of a given transistor ampli- 
fier?" This can be done by using the 
arrangement shown in Fig. 3. Measure 
voltages VI and V2 with an audio volt- 



AF 51G GEN (IHC) 



I 

— ^WSr- 
I0K 

VI 

J 



TRANSIGNER OR 
TRANSISTOR AM PL 



Fig, 3 — Method for determining trans- 
istor amplifier input impedance. 

meter. Then substitute the measured 
values in the equation: 

V2R 

Zf» = 

(VI -V2) 
to calculate the input impedance. 

To design a multistage transistor 
amplifier, you must start with the last 
stage and work toward the input end 
of the amplifier. As each stage is 
designed, record the component values. 
When optimum component values have 
been determined for all stages, you're 
ready to proceed with the construction 
of the miniature amplifier. The coup- 
ling capacitors can be 5-/uf miniature 
elect rolytics. A safe rule of thumb for 
determining the voltage rating is to 
make it equal or greater than the dc 
power supply voltage to be used in the 
miniature transistor amplifier. 



Parts for the transigner 

Resistors: 1—1.500 ohms, I watt; 2—22,000 ohms, 2 
watts; 1—1,000, 1—5,000, 1—7,500 (3-watt wirewound), 
| — 10,000, I — 100,000 ohms, I — 10 megohms, (logarith- 
mic taper), potentiometers. 

Capacitors: 2— 2-pf 200 volts; 2—20 \if, 1—40 \ii 
150 volts, electrolytics. 

Miscellaneous: I — Selenium rectifier, 20 ma; I — 
power transformer, secondary 75-110 volts; I — spdt 
switch; I — transistor socket; I — chassis; I— container 
for power-supply components. 

Optional: I — 0-l-ma meter; I — 100,000-ohm '/ 2 .watt 
resistor. 



In addition to being valuable in 
design work, the transigner can per- 
form other jobs. For example, the qual- 
ity of a transistor may be checked by 
recording the gain for several transis- 
tors, known to be good, in the tran- 
signer with a chosen value of dc sup- 
ply voltage, collector bias resistance, 
base bias resistance and input signal 
voltage at 1,000 cycles. These gain 
figures may be used as standards and 
a transistor of unknown quality may 
be checked against them. The high-fre- 
quency capabilities of the transistor 
may be checked by using an rf signal 
generator as the signal input source 
and a standard vtvm with rf probe for 
the measuring function. end 

43 



www.americanradiohistorv.com 



TELEVISION 



the Y 



signal in 



ATRIX OPERATION 



When excessive signals are applied 
to the picture tube, the Y voltages 
may also affect the picture hue 



Bv ROBERT G. MIDDLETON* 



M 



ATRIX response changes 
greatly when the Y signal 
level is varied. It is possible, 



off or 
picture 



for example, to cut 
energize the green gun in the r 
tube merely by varying the Y voltage 
while the chrominance signal voltage 
is held constant. 

Fig. 1 shows a familial' matrix 
arrangement used in many present-day 
color TV receivers. We will observe how 
this matrix responds to various levels 
of Y voltage while an R Y signal is 
applied to the color defectors. Fig. 2 
shows the output from the R — Y detec- 
tor when applying the R Y signal. 
For illustration, the output from the 
R Y detector is 7 volts; the output 
from the B Y detector is zero because 
a B Y detector cannot respond to an 
R — Y signal voltage. 

However, as shown in Fig. 2, the 
R — Y signal causes the G Y matrix 
to develop an output voltage, equal in 
this case to —3.6. Readers will recall 
that the G — Y matrix responds to a 
color signal voltage by adding 0.51 
(R-Y) to -0.19(B-Y), a G~Y out- 
put is obtained when an R—Y signal 
is applied to the color circuits. 

*Chief field engineer, Simpson Electric Co. 



The output voltages from tne R — Y 
detector and the G Y matrix are 
applied to the grids of the color pic- 
ture tube. In a low-level demodulation 
system the output voltages are amplified 
before application to the picture tube; 
in a high-level demodulation system 
the detectors operate at a sufficiently 
high voltage so that the output voltages 
from the detectors can drive the grids 
of the color picture tube directly. 

Figs. 3, 4 and 5 show how the re- 
sponse of the picture tube to an R Y 
signal varies in accordance with the 
voltage of the Y signal, applied to the 
cathodes of the picture tube. When 
the Y voltage is zero (Fig. 3) and 
the R-Y detector output is 7 volts, the 
result is 7 volts drive to the red gun, 
zero to the blue gun and 3.6 to the 
green gun. The red gun develops 
output because the signal is positive; 
the blue gun develops no output be- 
cause no drive is applied; the green 
gun develops no output because the 
signal is negative. Thus we will see a 
saturated red hue of low brightness 
when the color picture tube is driven 
by the signal voltages in Fig. 3. 

Fig. 4 shows the result of raising 
the Y signal from 0 to 3 volts, keeping 



LUMINANCE INPUT 



I RED GRID 



11 



CHROMA INPUT 



B-Y DO- 




GREEN GRID 
BLUE GRID 



Fig. 1 — A common matrix arrangement used in color TV receivers. 



R-Y*7V 



RED OUTPUT 
7V DRIVE 



-Y^OV BLUE OUTPUT 
0V DRIVE 



1 p~ 

Fig. 2 — Output of color detectors and 



Y*0V GREEN OUTPUT 
-3.6V DRIVE 



the output from the R Y detector at 
7 volts. (In discussing matrix opera- 
tion, a positive signal voltage increases 
the beam current from the gun, a nega- 
tive signal voltage decreases it. Thus, 
the signal voltages at the red gun are 
now additive and a total of 10 volts 
drive is applied to the red gun. The 
signal voltages at the blue gun provide 
3 volts of drive, the blue gun now 
producing beam current. The signal 
voltages at the green gun subtract, 
resulting in 0.6 volt drive to the 
green gun. Thus, the green gun is still 
cut off. Since there is output from the 
red and blue guns, the red hue is no 
longer pure. It is mixed with blue and 
a magnet a hue is produced. 

In Fig. 5, we see the result of further 
raising the Y signal voltage — to 5. As 
a result, the green gun is no longer cut 
off, developing beam current corre- 
sponding to 1.4 volts of signal drive. A 
greenish hue is now mixed with the red 
and blue hues. 

Y voltage in rainbow generators 

Let us apply the above to the display 
of rainbow patterns and see how hue 
may depend upon the value of Y signal 
voltage selected by the technician. A 
rainbow signal is a simple sine-wave 
voltage, usually set at 3.58 mc + 15,750 
cycles — the color subcarrier frequency 
plus or minus one horizontal scan. The 
color TV receiver then displays one 
rainbow spectrum, with a small portion 
lost on retrace. When the rainbow sig- 
nal operates below 3.58 mc the colors 
are reversed in their order as compared 
with the order when the rainbow signal 
is operating above this frequency. 



"" | G-Y;-3.6V r 



I ~" L 



RED OUTPUT 
JOV DRIVE 



BLUE OUTPUT 
DRIVE 



J 



L 



GREEN OUTPUT 
"6V DRIVE 



matrix when R-Y signal is applied. Fig. 3 — Tube drive when Y 0 volt. Fig. f— Tube drive when Y = 3 volts. 



44 



RADIO-ELECTRONICS 



www.americanradiohistorv.com 



TELEVISION 



A rainbow signal can be displayed 
on the screen of a wide-band scope 
having a triggered horizontal sweep or 
a conventional horizontal sweep capable 
of operating at 300 or 400 kc. The rain- 
bow signal then appears as shown in 
Fig. 6. The signal has the shape of a 
simple sine wave. Since the frequency 
of this rainbow signal differs slightly 
from the color subcarrier, it is often 
referred to as an offset color subcarrier. 

The rainbow signal has a constant 
voltage, depicted in Fig. 7 by repre- 
senting the signal voltage in the form 
of a circular sweep (constant radius) . 
The rainbow signal rotates in phase 
with respect to the color-subcarrier 
oscillator in the receiver because it has 
an offset frequency. (An ac voltage 
represented as an arrow — or vector — 
necessarily rotates with respect to an- 
other ac voltage having a different 
frequency.) And because the rainbow- 
signal vector rotates with respect to 
the color-subcarrier oscillator vector, it 
sweeps through the various hues indi- 
cated in Fig. 7. For this reason, a 
rainbow signal is sometimes called a 
linear phase sweep. It is a linear sweep 
because it has a constant rotating 
speed.; it is a phase sweep because its 
only variation consists of a change in 
phase with respect to the color-sub- 
carrier oscillator voltage. 

When the rainbow signal is applied 
to a color TV receiver, it is picked up 
only by the color detectors (see Fig. 1) ; 
no part of the rainbow signal passes 
through the Y amplifier since the color 
subcarrier frequency is trapped out in 
the Y amplifier. 

Since the rainbow signal is incom- 
plete (no Y-signal component), how is 
it possible to obtain visible patterns on 
the screen of the picture tube? This is 
done by introducing an artificial Y 
component via the brightness control. 
The master brightness control applies 
a dc bias voltage to the signal electrodes 
of the color picture tube. Thus the 
technician simply advances the bright- 
ness control to a point where the rain- 
bow colors appear satisfactorily on the 
screen of the picture tube. This is 
equivalent to having a Y signal of 
constant value. 

Returning to Figs. 3, 4 and 5, we 
can see that when the rainbow signal 
is sweeping through the R — Y phase, 



J ~ L 

J ~ ' u 



RED OUTPUT 
12V DRIVE 



BLUE OUTPUT 
"iV DRIVE 



J - L 



i GREEN OUTPUT 

nr- 1.4V DRIVE 

G-Y=-3^V I 

Fig. 5_Tube drive when Y = 5 volts. 
MAY, 1956 



we can obtain any one of the three 
conditions by adusting the master 
brightness control. That is, we can 
make the R — Y signal phase energize 
the red gun alone, the red and blue guns 
together or the red, blue and green 
guns together. 

Thus, the hue displayed on the screen 
of the color picture tube can be made 
to vary by adusting the value of the 
Y signal. However, it must not be 
supposed that this is always the case — 
the value of the Y signal in other (and 
more conventional) situations controls 
only the brightness and saturation of 
a color, without changing its hue. 

A standard NTSC color-bar signal 
for 100% saturated colors is shown in 
Fig. 8. This color signal has a lumi- 
nance and a chrominance component, 
as shown in Fig. 9. The three charac- 
teristics of a color, which concern mat- 
rix and picture-tube operation, are 
brightness, hue and saturation, which 
the matrix processes in terms of Y, 
R-Y, B Y and G-Y. R-Y and 
B — Y are distinguished by phase, being 
in phase quadrature (90°) to each other. 
The chrominance signal in Fig. 9-a is 
a mixture of R — Y and B — Y. 

As a simple illustration of the effect 
of the Y component in controlling 
brightness and saturation, consider the 
following three red color signals: 

1. Signal for 100% saturated red at 
full brightness: 

Y = 0.30 
R Y 0.70 
B Y = 0.30 
G + Y = -0.30 

2. Signal for 50% saturated red at 
full brightness : 

Y = 0.65 
R-Y 0.35 
B - Y = -0.15 
G - Y = ~ 0.15 

3. Signal for 100% saturated red at 
half brightness : 

Y 0.15 
R - Y = 0.35 
B Y = - 0.15 
G Y = -0.15 

The voltages in these three red sig- 
nals show that the only difference 
between 100% saturated red at half 
brightness and 50% saturated red at 
full brightness in the Y component. 

This, then, leads to the question, 
"Why do we observe cases of matrix 
operation in which the value of the Y 
component affects hue, while in other 
cases the value of the Y component 
affects only brightness and saturation?" 
The answer to this is that the value of 
the Y component can change the hue 
only when the relative values of lumi- 
nance and chrominance voltages are 
such that the dynamic operating range 
of the color picture tube is exceeded. 

Thus, it can be stated: The role of the 
Y signal in matrix operation is control- 
ling the brightness and saturation with 
no control of hue, during normal opera- 
tion of the picture tube. end 




Pig. 6 — Waveform of rainbow signal. 



>-n^0RANGE 

/ \ 

ZyaL0W-0RANGE\ 


JRIGHT RED #Sv 

AlACENTA \ 
/(G-Y) 

/ .✓'REDDISH BUJE 1 
L/^ R-Y BLUE-PURPLL-J 


■mi (if sSfcfl . 

BURST REF 

XV^BLLOWSH /,FFU 
GREEN 


\ ^\£REENISH BLUE / 

BLUISH \ jr 
GREEN JSl 



Fig. 7 — Color phase relationships. 




Fig. 8— Standard NTSC color -bar signal. 




Fig. 9-a (top) — 5.58-mc chrominance 
component of color-bar signal; 9-t> (bot- 
tom) — luminance. 




45 



www.americanradiohistorv.com 



TELEVISION 




TROUBLESHOOTING 



Weak picture due to defective a.g.c. 



A.G.C 



CIRCUITS 




Snow caused by excessive a.g.c. voltage. 



By CYRUS GLICKSTEIN 

A G.C. (automatic gain control) 
/ \ troubles in TV receivers are 
/ \ often tough to find. This is 
not because a.g.c. circuits are 
more complex than most other TV cir- 
cuits — the a.g.c. system is usually one 
of the simpler circuits. The difficulty 
arises because most of the symptoms 
resulting from a.g.c. faults are exactly 
the same as those produced by familiar 
troubles in other sections of the re- 
ceiver. 

In some cases, the defect may im- 
mediately point to possible trouble in 
the a.g.c. circuit: 

Normal signal input at the antenna 
produces video overload (too much 
contrast), with the contrast control 
having less than the usual range of 
control, while sound is normal; 

Sound is O.K. but the screen is blank 
(no picture or raster) on active chan- 
nels at normal brightness settings — 
on inactive channels a normal raster 
is visible. (This indicates the picture 
tube is blanked out with normal signal 
input as a result of video overload.) 

The following symptoms may be 
caused either by a.g.c. troubles or 
faults, as indicated in parentheses, in 
other sections of the receiver: 

1. Tearing, bending, erratic hori- 
zontal hold action or other hori- 
zontal instability (front end, 
video strip, sync section, horizon- 
tal a.f.c, horizontal sweep cir- 
cuit) . 

2. Defective vertical and horizontal 
sync (front end, video strip, sync 
section) . 

3. No sound, no pix, raster O.K. 

46 



Part I— Types and operation 
of a.g.c. systems 




6BK5 

VIDEO AM PL 
VIDEO TEST POINT 
® 



II 



TO SOUND If ^ 



2.2Wif TO PEAKING CKT 




I j video ampl output 

NEG VOLTAGE PROPORTIONAL TO AVERAGE DEI LEVEL 



NEC VOLTAGE PROPORTIONAL 
AMr-j T0A/ER*GE-T0-PtAK0F 
INCOMING SIGNAL 



I20K .0033 18 K 



R266-l.8MEG-5% 

Fig. 1 — Schematic diagram of the a.g.c. circuit in the Du Mont RA-312 chassis. 




6BC5 6CB6<3) 

RF AMPL BT VBEO IF AMPL 2ND VIDEO IF AMPL 3RD VIDEO IF AMPL 




[•jOOI >UMEG t»D0I5 




VIDEO DET 



*T*470|;Mf 6AL5 
AGC DET 



■AW 



.005 

Hi- 



Fig. 2 — Simple a.g.c. with separate a.g.c. rectifier in Silvertone 478.380. 



6CB6 

1ST IF AMPL 



*~1 



jjo <I0K 




6CB6 
2ND IF AMPL 



Tnnn row 



I80K 

^22nyt J jC> o|27K^^ 2 
y RF AMPL GRID 



PIN 7 





~~ J22 6AU6 
2.SMEGJ GaT£Dagc 



PART OF H0RIZ OUTPUT TRANS 
.001 g] 



fvVW 

6.8 K 47 |i (if 

I00V 

kl2BY7 

VIDEO AMPL 



TO CRT CAT 



PERFORMANCE C0NT 
2.2 MEG 




&/ ??A^ I25V 47K 

-t — Wr 



V I480V 

Fig. 3 — Gated a.g.c. with threshold control in a.g.c. bus — Sparton 23U214. 

RADIO-ELECTRONICS 



www.americanradiohistorv.com 



TELEVISION 



(front end, common i.f. stage, 
video detector and possibly video 
amplifier in intercarrier sets). 

4. No pix, sound normal, raster 

0. K. (video strip in split-sound 
receivers, video amplifier in in- 
tercarrier sets when sound is 
taken off at the video detector). 

5. Weak (snowy) pix (see photo), 
weak sound (front end, com- 
mon i.f., video detector and pos- 
sibly video amplifier in inter- 
carrier sets). 

6. Weak video (see photo), loss of 
horizontal and vertical sync, 
sound O.K. (video strip). 

7. A change of sensitivity in both 
video and sound as the set is 
operating (front end, common 

1. f., video detector and possibly 
video amplifier in intercarrier 
sets). 

8. Video hum pickup (front end, 
video strip). 

The a.g.c. circuit is usually consid- 
ered part of the video strip which also 
includes the video (or common) i.f. 
stages, the video detector, the video 
amplifier and the picture tube. Thus, 
the a.g.c. circuit must be kept in mind 
as a possible source of trouble when 
symptoms point to a defect in the 

Front end or common portion of the 
video strip (no sound, no pix, raster 
O.K.); 

Video strip (weak or contrasty video 
or no video, sound and raster O.K.) ; 

Sync section, horizontal a.f.c. or 
sweep circuits (poor horizontal or ver- 
tical sync). 

Therefore an a.g.c. circuit check 
should be made a part of normal 
troubleshooting when these symptoms 
are noticed. 

A.g.c. systems 

Two basic types of a.g.c. systems are 
commonly used: simple and keyed 
(gated). A third type, found in several 
recent models, can be considered a 
combination of the two (Fig. 1). A 
similar circuit in a current Zenith 
model is labeled noise-gated amplified 
a.g.c. A fourth variety — amplified 
a.g.c. — was used in a number of models 
before the keyed a.g.c. system became 
so popular. There are of course many 
variations of each of these major 
types. Fig. 2 shows a simple a.g.c. cir- 
cuit, using an a.g.c. diode rectifier. 

Simple a.g.c. is similar to a.v.c. in 
radio receivers. The rectified and fil- 
tered video i.f. signal produces a nega- 
tive d.c. output voltage based on the 
peak value of the i.f. input. In simple 
a.g.c. systems noise bursts and high 
noise levels tend to add to the normal 
a.g.c. voltage. This increases the ad- 
verse effect on the signal unless noise 
cancellation circuits are used. 

A keyed a.g.c. system is shown in 
Fig. 3 and is used in many recent 
models. The keyer tube, which is biased 
to cutoff by a high cathode voltage, 
conducts only during the period when 
the positive peaks of the video signal 
(horizontal sync pulses) are applied to 

MAY 1956 



the grid. At the same time, a narrow, 
positive square wave derived from the 
horizontal sawtooth retrace is applied 
to the plate from the horizontal out- 
put circuit. Plate current, therefore, 
flows only during the sync pulse inter- 
val. The plate circuit has an a.g.c. 
filter network that charges to a nega- 
tive voltage in accordance with the 
signal strength. Noise pulses between 
sync pulses have no effect in develop- 
ing a.g.c. bias since the tube is cut off 
during these intervals. 

In the noise-gated amplified a.g.c. 
circuit shown in Fig. 1, the video sig- 
nal from the plate of the video ampli- 
fier is applied to grid 3 of the 6BE6 
first sync clipper. Grid rectification oc- 
curs, developing a negative voltage at 
this point which is applied to the a.g.c. 
Tine. At the same time, a negative volt- 
age is developed at the video detector 



Pff.SE FROM HORIZ 6AU6 TO AGC BUS^ 



OUTPUT TRANS 
C.OUPflSlTF VIDEO I =: 




GC 


KEYER 


FROM VIDEO AMPL \ 




1.1 


K « 


>,5K B+ 

Jagg threshold cont 



Fig. 4 — The a.g.c. threshold control 
is in cathode circuit of keyer tube. 

output which is also applied to the 
a.g.c. line. The resulting a.g.c. bias 
at the junction of R2G6 and R262 is a 
function of the peak signal input at 
the antenna terminals of the receiver. 
(The 6BE6 also functions as a noise- 
cancellation stage. Video signals of 
opposite polarity are applied to grids 
1 and 3. The normal amplitude of each 
allows sync pulse output to appear at 
the plate. However, large noise pulses 
in the video signal act to cancel each 
other in the output of the stage.) 

A.g.c. action 

The primary function of a.g.c. is to 
keep the output picture level relatively 
constant with changes in signal 
strength (peak signal level) at the an- 
tenna terminals. Like a.v.c. in radio, 
this is done by making a strong sig- 
nal develop more a.g.c. bias, applied 
through the a.g.c. bus to the grids of 
the r.f . and video (or common) i.f. 
amplifier stages, to reduce amplifica- 
tion. A weak signal produces less a.g.c. 
bias. Therefore, r.f. and video (com- 
mon) i.f. amplification is greater. 

However, if a comparatively weak 
signal were allowed to develop any a.g.c. 
bias, the result would be a still weaker 
signal. This is undesirable, especially 
in fringe areas where the signal-to- 
noise ratio is low. For this reason many 
receivers with a.g.c. have controls or 
switches in the a.g.c. system for select- 
ing the level of signal strength at which 
the a.g.c. becomes operative. 

Manual a.g.c. controls fall into two 



main groups : local-distance switches 
and a.g.c. threshold controls. Auto- 
matic a.g.c. delay networks generally 
use either a clamping diode or a bias 
applied to the a.g.c. diode rectifier. 
Some models use one or more of these 
devices in the a.g.c. system (Figs. 1—4). 
Other receivers with a.g.c. may use 
none. The local-distance switch shorts 
out part or all of the a.g.c. voltage to 
the r.f. amplifier (and in some receiv- 
ers, the other controlled stages) in the 
distance position. This allows the r.f. 
amplifier (and in some receivers, the 
other controlled stages) to operate 
with little or no a.g.c, permitting 
greater amplification of weak signals 
with a resultant improvement in the 
signal-to-noise ratio. 

The threshold control is generally a 
potentiometer connected in a voltage- 
divider network. In some models, this 
control (Fig. 1) varies the bias to the 
a.g.c. keyer tube so that the stage does 
not operate until a given level of video 
signal is present. Above that level, the 
tube operates and applies a.g.c. 

In other models the threshold con- 
trol varies the voltage applied to the 
a.g.c. bus — usually to that section of 
the bus connected to the r.f. amplifier 
(R317, Fig. 1; performance control, 
Fig. 3). In this type of circuit it is 
generally used together with a clamping 
diode. In the circuit of Fig. 4 no nega- 
tive voltage appears on the entire a.g.c. 
bus until the video signal is above the 
level selected by the threshold control 
setting. In Figs. 1 and 3, some a.g.c. 
voltage is developed even at low signal 
levels but no a.g.c. bias is applied to 
the r.f. amplifier stage until the video 
signal is above, the threshold setting. 

A clamping diode is connected from 
the a.g.c. bus to ground (V209, Fig. 1; 
V13-b, Fig. 3). At low signal levels, the 
diode conducts and clamps the point 
where the diode plate is connected to 
ground potential. No a.g.c. voltage is 
developed at this point. When the video 
signal rises above a given level, the 
voltage at the clamping diode plate 
becomes negative and the diode no 
longer conducts. A.g.c. voltage is then 
developed. 

When a threshold or delay control 
is used with a clamping diode as in 
Figs. 1 and 3, the level at which a.g.c. 
bias begins to be developed can be 
varied. If the control is rotated so the 
voltage at the center tap is more posi- 
tive, a stronger video signal is neces- 
sary to bring the voltage at the diode 
plate below ground potential and so 
cause the clamper to cut off. 

Fig. 2 shows a simple a.g.c. delay 
network which makes use of a bias 
voltage applied to the a.g.c. rectifier. 
The cathode of the a.g.c. diode is con- 
nected to the cathode of the last video 
i.f. amplifier. The small positive volt- 
age applied to the a.g.c. rectifier cath- 
ode keeps the tube cut off until the 
signal level at the diode plate is large 
enough to overcome this biasing volt- 
age. A.g.c. voltage is then developed 
in the usual way. TO be continued 

47 



.com 



TELEVISION 



Field Service 

Experiences 

with 

COLOR TV 



A review of common 
troubles the service technician 
may expect to find 

By CHARLES W. RHODES* 

A SIDE from the routine component 

t \ breakdowns in color receivers, 
m \ which have their counterparts 
in monochrome chassis, a few 
new problems have developed to chal- 
lenge the service technician who has 
turned his attention to color. 

One common trouble is intermittent 
color reception. I have seen cases where 
slight changes in antenna orientation or 
lead-in placement caused loss of color. 
At first the trouble appeared to be in 
the antenna system. However, the color 
didn't grow weaker gradually; it dis- 
appeared abruptly and in each case 
varying the hue control also caused loss 
of color, often just as the correct set- 
ting of the control was approached. 

Actually the trouble had nothing to 
do with either the antenna or hue con- 
trol. The clue is the abrupt loss of color. 
It is caused by the color killer circuit 
which biases the chrominance amplifier 
beyond cutoff during monochrome re- 
ception to prevent noise pulses from 
passing through the chrominance cir- 
cuits and causing color specks on the 
screen. 

Fig. 1 shows a widely used color killer 
circuit. During color reception the burst 
signal is rectified by V4 which develops 
a high negative bias at the plate of 
V4-b. This is applied to color killer VI 
and cuts off plate current. The plate 
voltage of VI then rises to B plus, 150 
volts. 

Chrominance amplifier V2 is direct- 
coupled to VI, its cathode being re- 
turned to B plus. Plate current flow 
through VI lowers the grid voltage of 
V2, cutting it off whenever the burst 
signal is not present — during mono- 




chrome transmission. It is not possible 
for both VI and V2 to conduct at the 
same time, and for color reception VI 
must be cut off to allow the chrominance 
signals to reach the color demodulators 
via V2. 

Frequently, the rectified burst signal 
is not strong enough to completely cut 
off VI although it can synchronize the 
color oscillator. This is the real cause of 
many cases of intermittent color recep- 
tion. When this trouble is suspected, the 
VI cathode lead to ground should be 
opened, disabling the killer circuitry. 
Many technicians have installed a 
switch between the killer cathode and 
ground. If the receiver must operate on 
marginal signals, it is best to open the 
switch. 

Another frequent cause of intermit- 
tent color reception, where monochrome 
pictures are received properly, is an 
intermittent color subcarrier oscillator. 



Fig. 2 shows a widely used crystal- 
controlled oscillator circuit. Here the 
tube may check perfect but will refuse 
to oscillate — several tubes should be 
tried. 

Tuning cathode coil L4 is very cri- 
tical. As this coil is tuned toward reso- 
nance from one side, output rises until 
resonance is reached and the oscillations 
cease. 

Tuning L4 too close to resonance will 
cause intermittent operation. A con- 
venient way to adjust L4 properly is to 
connect a v.t.v.m. to the plate pin of 
V4-b (Fig. 1), setting the meter to read 
on a -30-volt scale. Remove V3 so that 
the voltage read at the plate is only the 
oscillator output fed from V7, the sub- 
carrier buffer amplifier. Tune L3 first 
for maximum output. Then back off the 
slug to start oscillations again. Finally 
tune it to give exactly 2 volts less out- 
put than the maximum you obtained. 
This is sufficient output for the demodu- 
lators and yet is far enough from reso- 
nance that drift will not cause it to 
stop oscillating. 

In this circuit, feedback to sustain 
oscillations is through the grid-cathode 
capacitance of the oscillator tube and a 
2.2-/i/if capacitor, generally a 5% NPO 
unit. In some cases where L4 was prop- 
erly tuned, and several oscillator tubes 
have been tried without success, an 
erratic oscillator has been cured by 
increasing this capacitance to 4.7 or 
even 6.8 ft/if, using only 5% NPO units. 
This will require retuning L4. The 
crystal itself has given us very little 
trouble. 

Defects in the reactance control tube 
(V5) and its circuit may stop the oscil- 
lator (V6). V5 behaves like a variable 
tuning capacitor shunting L3 and the 
crystal, thereby controlling the oscilla- 
tor frequency. Its shunting capacitance 
depends upon its transconductance 
which varies with electrode voltages 
and the values of C3 and R2. Leakage 
in C3 would cause the grid to go posi- 
tive, increasing the capacitance beyond 
limits. If either C3 or R2 increases in 
value, excessive capacitance will shunt 
the crystal and it won't oscillate. If 



•Northwestern district service manager, CBS- 
Columbia. 

48 




RKRT OF QUADRATURE TRAN5 



Fig. 1 — Schematic shows simplified color killer and a.f.c. circuitry. 

RADIO-ELECTRONICS 



www.americanradiohistorv.com 



either is too low in value, there may be 
very little a.f.c. action and color sync 
will be poor. 

Many cases of erratic shifts in hue 
in the color picture, notably with cam- 
era changes, have been traced to hori- 
zontal oscillator alignment. The burst 
signal is transmitted during part of the 
horizontal blanking or retrace time. A 
pulse from the flyback transformer 
forces the burst amplifier to conduct for 
its brief duration and then cuts it off 
during the active scanning period so 
that chrominance signals cannot enter 
the burst circuits which would be analo- 
gous to letting raw video pass through 
the sync circuits. This would cause the 
hues to change with picture content. 
Chrominance signals may enter the 
burst circuits if the horizontal keying 
pulse (retrace) is delayed too long and 
part of it occurs during active scanning- 
time. In monochrome receivers we refer 
to this as a left-hand horizontal fold- 
over. The cure is to align the horizontal 
oscillator very accurately. Synchroguide 
circuits commonly give this trouble. 

Tinting of monochrome pictures, 
causing some areas to be greenish or 
magenta, is a frequent shortcoming of 
color picture tubes. This is a special 
case of impurity which can exist even 
though perfectly pure individual fields 
of red, green and blue are obtained. It 
is a defect for which there is no remedy. 
Individual fields may be checked for 
purity by turning down the screen con- 
trols for the other two guns in sequence. 
The contrast control must be turned 
fully off for checking purity. With the 
green and blue screens off, the resulting 
red raster should be pure red. If not, 
the usual purity adjustments should be 
made. Generally, when the red field is 
pure, the green field will also be and 
the blue field is almost sure to be pure, 
but they should be checked as well, in 
any case. 

Where the three individual fields are 
found to be pure and tinting exists in 
the white raster, the trouble is either a 
hum or a low-purity picture tube. Hum 
may be isolated by bypassing: the cath- 
odes and grids of the picture tube with 
a suitable capacitor or by removing the 
video tubes which drive the picture tube. 
Hum will form one or two horizontal 
bands. As tube manufacturing tech- 
niques improve, this problem will di- 
minish. 

The extremely high anode voltage of 
color picture tubes may produce some 
freak breakdowns of components. Oc- 
casionally the high voltage can momen- 



tarily break down the insulation of the 
picture- tube glass envelope and arc 
through to a nearby component such as 
the purity coil, convergence assembly 
or yoke. This has explained some mys- 
terious failures of these parts or as- 
sociated controls. The energy stored in 
the high-voltage supply is far greater 
than in monochrome receivers and con- 
sequently more lethal. 

A few color receivers have been made 
using the Standard Coil turret tuner 
which uses R strips. In some u.h.f. 
areas, these strips produce a picture i.f. 
of about 42.0 mc and a sound i.f. of 46.5 
mc. Monochrome reception is satisfac- 
tory. However, the sound i.f. is not 
trapped out and very heavy interfer- 
ence on color programs occurs as a 
result. 

In cases where the hue control is not 
centered in its range but tunes at the 
extremes of its rotation, it may be pos- 
sible to center it. But considerable cau- 
tion is required. 

Fig. 1 shows how the burst signal is 
taken off the plate of a video amplifier 
in many color receivers and fed to the 
keyed burst amplifier. The chrominance 
signals are taken off earlier in the video 
amplifier. Components Ll-Cl form a 
trap tuned to 3.579 mc to prevent the 
burst signal from reaching the color 
tube. It is capacitively coupled to L2-C2 
in the grid of the burst amplifier. Capac- 
itor C2 is a small variable unit which 
can tune the circuit slightly above or 
below 3.579 mc and is the hue control. 
When it is tuned to resonance, there is 
no phase shift and the burst signal is 
passed at maximum amplitude to the 
burst amplifier. If the hue control is 
tuned lower than 3.579 mc, the burst 
signal is reduced in amplitude and 
shifted in phase. Tuning above 3.579 
mc also produces attenuation and a 
phase shift opposite to that produced 
before. This phase shift determines the 
hue of reproduced colors and is a cus- 
tomer control. 

While the slug in L2 could be ad- 
justed to center the range of the hue 
control, it may result in further de- 
tuning which results in additional and 
unwanted attenuation of the burst sig- 
nal. Should 3.579-mc trap Ll-Cl or the 
burst transformer be slightly out of 
alignment, they can produce phase 
shifts which the customer may counter- 
act by detuning the hue control in the 
opposite direction. 

The safer plan is to follow the manu- 
facturer's instructions and realign all 
these coils together. end 



TELEVISION 

FM-TV ANTENNA SWITCH 

WHEN a single antenna is used for 
both FM and TV, it is seldom sat- 
isfactory to connect both receivers di- 
rectly to the lead-in because this usually 
causes mismatch and losses. A d.p.d.t. 
switch is one answer to the problem, 
but it is easy to forget to switch from 
one set to the other. 

A relay in the antenna circuit pro- 
vides a simple, automatic and foolpioof 
method of switching the antenna. A 
d.p.d.t. relay with a 115-volt a.c. coil 
should be connected as shown in the 
diagram. This relay may be a Potter 
& Brumfield KR11A, Leach 327, 
Advance AM/2C/115VA or equivalent. 

TO TV ANT TERMINALS 




FROM ANT TO FM TUNER 

Mount the relay on the TV chassis 
as close to both the power supply and 
tuner input as is convenient. Tie the 
relay coil directly across the primary 
of the power transformer. Use a short 
section of 300-ohm ribbon type trans- 
mission line to connect the normally 
open contacts of the relay directly to 
the antenna terminals on the TV set. 
Connect the armature contacts to the 
antenna lead-in through a plug-and- 
socket type of TV antenna connector. 
The normally closed (back) relay con- 
tacts are connected to the FM antenna 
terminals through a section of trans- 
mission line and a connector. Polarize 
the connectors as shown in the diagram. 

This arrangement leaves the antenna 
connected to the FM receiver whenever 
the TV set is turned off. But, when the 
TV receiver is in use, the relay coil is 
energized and transfers the antenna 
from the FM to the TV set. When 
pulling the TV chassis for inspection 
or repairs, simply separate the connec- 
tors to the antenna and FM tuner and 
plug the antenna lead into the FM 
connector. The TV receiver and relay 
may then be remo\ 3d without interrupt- 
ing the use of the FM set.— R. D. Her- 
locker END 

49 




3.579545MC OUTPUT TO BUFFER AwPL V7 



Fig. 2 — Typical color subcarrier oscillator circuit. 



MAY, 1956 



www.americanradiohistorv.com 



Methods and tecliniques used 
in closed-circuit operation 



INDUSTRIAL 




is simple 



By EDWARD M. NOLL* 



TELEVISION camera tubes and 
circuits are no more complex or 
difficult to learn than receiver tech- 
niques. In closed-circuit industrial 
TV the simplicity of the composite 
television signal makes the system 
much less complex. Compared to the 
elaborate signal construction for com- 
mercial telecasting, the closed-circuit 
composite is less exacting and has 
fewer pulse components. 

The first hurdle is to understand 
that circuit functions at the camera 
tube are almost identical to those at 
the picture tube (Fig. 1). For example, 
there must be a source of electrons in 
the form of a cathode-ray gun. The 
beam of electrons must be set in motion 
horizontally and vertically to form a 
raster on the target image. Thus hori- 
zontal and vertical deflection wave- 
forms must be generated to deflect the 
camera-tube beam. Just as at the pic- 
ture tube, the camera -tube beam must 
be made inactive during retrace in- 
tervals. Therefore horizontal and ver- 
tical blanking pulses are needed at the 
camera tube. The basic difference be- 
tween camera and picture tubes is that 
the scanning beam at the camera tube 
produces a video signal as it scans a 
phototarget surface; at the picture 
tube the scanning beam causes a 
fluorescent screen to glow as a function 
of the video information. 

There must be synchronized motion 
of the picture-tube beams; the synchro- 
nizing pulses perform this service. 
They insure that the image on the pic- 
ture tube is reproduced in the same 
sequence the image video information 
was released at the camera tube. 
Synchronizing pulses are formed by 
the pulse generator section of the 
camera and supplied to the deflection 
systems of both camera and picture 



Installing the RCA 
automatic iris. 



*Author Closed Circuit and Industrial Television, 
Macmillan. 1956. 

RADIO-ELECTRONICS 



www.americanradiohistorv.com 



TELEVISION 




The Kay Lab industrial TV camera. 



tubes. Consequently the motion of the 
two scanning beams is synchronized. 

Simultaneously timed blanking pulses 
also go out from the pulse generator 
to the camera and picture tubes to pre- 
vent release and display of spurious 
retrace signals. 

Interconnection plans 

There are a number of methods of 
sending the video and synchronizing 
information between camera and view- 
er. For many installations (Fig, 2-a) 
a standard television receiver functions 
as a viewer. The synchronizing and 
video signals are used to modulate a 
low-power r.f, oscillator tuned to a 
frequency of one of the v.h.f. television 
channels. Therefore the television sig- 
nal can be carried by a transmission 
line (300-ohm or coaxial) between 
camera and antenna input terminals 
of the television receiver. 

With this method there is no need to 
modify any existing television receiver 
as the signal input contains the con- 
ventional r.f. and video components and 
the horizontal and vertical syncronizing 
pulses. Of course, the disadvantage here 
is the relative complexity of the signal. 

A second common system (Fig. 2-b) 
is to send the composite video and 
synchronizing signal over a coaxial 
cable to the video amplifier input of the 
viewer. For this method an r.f. carrier 



is not required. However, sync sep- 
arator circuits are needed at the viewer 
to break down the composite television 
signal into its basic components of 
video blanking, horizontal and vertical 
sync. 

A final arrangement (Fig. 2-c) is one 
that sends each basic signal component 
separately to the viewer. The first two 
methods require but one line to link 
camera and viewer. When signal com- 
ponents are sent separately, three lines 
(multiconductor cable) carry signals 
between camera and viewer. In this 
plan the sync signals are applied 
directly to the horizontal and vertical 
deflection generators. Sync separators 
are not required. 

The first method is convenient when 
standard television receivers are used 
as viewers since chassis need not be 
worked upon. The second method does 
not use any r.f. carrier and bypasses 
the r.f. and i.f. processes. The third 
arrangement eliminates the sync sep- 
arator circuits but requires a multi- 
conductor cable. 

Signal makeup 

The simplicity of the composite tele- 
vision signal for an industrial system is 
amazing. Such complex waveforms as 
equalizing pulses, serrated vertical sync 
pulses, etc., are not necessary in a 
clos< id-circuit system. In fact, as shown 



in Fig. 3, the front and back porches 
of the combined horizontal sync and 
blanking pulses need not be present. 
As a result one pulse serves both the 
sync and blanking functions. Thus, 
two pulses can meet the requirements 
of a small closed-circuit system — ver- 
tical and horizontal sync-blanking 
pulses. If the horizontal pulse rate is 
set near the line frequency of 15,750 
cycles and vertical pulse rate at 60 
cycles this simple signal construction 
is able to lock in a standard television 
receiver. In fact if the horizontal 
oscillator is stable, and its frequency 
set critically, an interlaced pattern 
can be attained. 

Even an interlace system for use in 
a more elaborate industrial installation 
can be established with a less complex 
composite synchronizing signal than is 
used in commercial telecasting. Instead 
of equalizing and serrated vertical 
pulses, a short-duration carefully timed 
vertical sync pulse (Fig. 4) is used. 
This pulse is inserted so that its lead- 
ing edge coincides with the leading 
edge of one of the horizontal sync 
pulses during one vertical retrace 
interval. The very next vertical sync 
pulse occurs halfway between two 
horizontal pulses. Thus the second 
vertical retrace is timed to occur at 



VIDEO 




AM PL 





GENERATED VI0E0 INFORMATION 



STAGE FOR 
INSERTION OF SYNC 
4 BLANKING PULSES 



H0R1Z iVERT 
BLANKING PULSES 



HORiZ AVERT 



SYNC PULSES 





HORIZ DEFL 


HORIZ COILS 


SYSTEM 



VERT COILS 



VERT DEFL 
SYSTEM 





COMPOSITE 

TVSIG 

AMPL 


TRANSMISSION 


VIDEO 




VIDEO 




SYSTEM 


AMPL 




AMPL 



SYNC 
SEP 



VIDEO 4 
BLANKING 



Pit 



HORIZ 
DEFL 
SYSTEM 



HORIZ COIL^, 



VERT 
DEFL 
SYSTEM 



Fig. 1 — Block diagram shows basic plan. 



VIDEO 




PULSE 




MODULATED 


AMPL 




INSERTION 




OSC 




PULSE 
INSERTION 



Z 



COMPOSITE 
TV SIG 
AMPL 


COAX 


VIDEO 




VIDEO 




AMPL 




AMPL 



SYNC 

SEPARATORS 



VIDEO A 
\ 'BLANKING 



Ml 



HORIZ 

pulse's 



HORIZ 
DEFL 
SYSTEM 



HORIZ^ 



VERT 

DEFL 
SYSTEM 




MAY, 1956 



Fig. 2 — Diagrams show systems used 
in industrial television transmission. 

51 



www.americanradiohistorv.com 



TELEVISION 



a half-line position — a necessary rela- 
tion for interlace. 

Television camera 

The RCA vidicon camera tube (see 
photo) has been responsible for initial 
successes in industrial television. It 
has high sensitivity, minimizes light- 
ing problems, is very small and permits 
design of lightweight and compact tele- 
vision cameras. Equally important is 
that its associated circuits need not 
be elaborate. For example, the top 
anode voltage is only about 300. Thus 
a separate high-voltage supply is not 
required. As the vidicon has a low- 



HORlZ SYNC 



HORIZ" _ 
ULANKING 



II BLK LEVEL B 



PLAT-TOP FOR 8LANKJNG 



LEADING EDGE 
FOR SYNC 




COMMERCIAL TV 
UNE INTERVALS 



CLOSED -CKT -TV 
UNE- INTERVALS 



SYNC-8LANKJNG PULSES 

Fig. 3 — Signals for standard tele- 
vision and closed-circuit systems. 



COINCIDES WITH HORJZ PULSE VERT SYNC PULSES 



1ST FIELD 
RETRACE 




OCCURS HALfWAY BETWEEN HORlZ PULSES 

Fig. 4 — Producing vertical interlace. 

velocity scanning beam the deflection- 
circuit power requirements are rela- 
tively low. 

All the factors mentioned — wired 
connection to receiver or viewer, sim- 
plicity of signal construction and the 
vidicon — permit construction of an al- 
most unbelievably small television 
camera. For example, the Dage camera 
(see photo) uses only eight tubes in- 
cluding camera tube. The camera meas- 
ures only 10 x 6Y2 x 4V2 inches. It 
can supply a video-modulated r.f. sig- 
nal directly to the antenna terminals 
of a receiver or a straight video signal 
for application to the video amplifier 
input of a viewer. 

The circuit functions within the 
camera are shown in Fig. 5. Video 
signal output of the camera tube is 
amplified by a seven-stage video ampli- 
fier consisting of four tubes. Three of 
these tubes have dual functions. The 
fourth stage is a phase corrector or 
so-called "high peaker" which corrects 
for the high-frequency de-emphasis that 
occurs at the output circuit of the 
camera tube. 

In the fifth stage horizontal blank- 
ing and sync are inserted in the video 
signal; vertical sync blanking is added 
in the sixth stage. The final amplifier 
is a video output stage supplying com- 
posite video to an output jack and 
succeeding video modulator. One dual 
triode functions as video modulator 
and r.f. oscillator. It supplies a video- 
modulated television signal to the out- 
put jack. 

The pulse generator is a four-stage 
52 



1ST 


2ND 


VIDEO 


VIDEO 


AMPl 


AMPL 



3RD 


4TH 


VIDEO 


VIDEO 4 


AMPL 


PHASE 




CORRECTOR 



5TH 


6TH 


VIDEO & 


VIDEO A 


HORIZ 


VERT 


PULSE 


PULSE 


INSERT 


INSERT 



VlDlCON 



CAMERA HORIZ BLANKING 



VERT SYNC-BLANKING 



7TH 

VIDEO 

OUTPUT) 



INSERTED HORIZ SYNC- BLANKING 



fcO'VSIG FROM RECTIFIER 


VERT 

DISCH 




VERT 
OUTPUT 




HOPJZ 
OSC 




HORJZ 
OUTPUT 









VERT COLS 



CAMERA TUBE DEFL SIGNALS 



HORIZ COILS 



SEL RECT 
PWR SUPPL 



Fig. 5 — Block diagram shows circuits in the Dage 60 industrial TV camera. 



segment of the camera containing ver- 
tical discharge and output stages and 
horizontal oscillator and output stages. 
The vertical discharge tube forms a 
vertical sawtooth, being excited by a 
60-cycle waveform from the power 
supply. The vertical sawtooth drives 
the vertical output stage which develops 
the camera-tube deflection current in 
the vertical coils. A pulse is removed 
from the discharge tube cathode to be 
used as video-inserted sync blanking 
and as vertical blanking for the camera 
tube. The horizontal oscillator and out- 
put stages perform similar functions 
in the formation of the horizontal 
pulses and horizontal deflection energy. 

Many special accessories are being 
developed for use with industrial tele- 
vision cameras. They improve the ver- 
satility and reliability of industrial in- 
stallations. For example, RCA now has 
a number of accessories such as remote 
optical focusing of camera from moni- 
tor viewer, weatherproof housing, ex- 
plosion-proof housing, extension video 
amplifier to increase spacing between 
camera and viewer, underwater units 
and automatic iris. 

The automatic iris (see photo) com- 
pensates for changing light levels to as- 
sure TV pictures of constant brightness 
and contrast. Thus the television system 



functions without readjustment as the 
brightness levels change. 

The actual iris, which resembles a 
roll of 35-mm film, is mounted with 
motor-driven regulators. The film serves 
as a filter and is continuously graded 
in density. As external light levels 
change, the film automatically unreels 
between camera lens and vidicon until 
a filter of proper density for the light 
condition moves into place. 

Weatherproof housing for the Kay 
Lab industrial camera is shown in an- 
other photo. The unit contains a heater 
for cool- weather, fan for hot-weather 
operation, plus a windshield wiper for 
mist and rain. All accessories can be 
made to operate automatically. The Kay 
Lab camera is also excellent for picking 
up slides or film directly from a projec- 
tor — the projector is focused on the 
sensitive surface of the vidicon. Thus 
film can be run and presented simul- 
taneously on a number of viewers in 
different locations. This is an excellent 
educational tool. 

The field of closed-circuit and indus- 
trial television is new and exciting. 
There are many applications and tech- 
niques to be explored. It is important 
that the television technician pay close 
attention to the field and keep abreast 
of its development. end 




"Now then, how long have you been a half- wave rectifier?" 

RADIO-ELECTRONICS 



www.americanradiohistorv.com 



TELEVISION 






Photo shows poor picture focusing. 



VttO IN 



TO BRIGHTNESS CONT 



PIX 

2IATP4 



150V 



FOCUS 



p 26QV 



1260V 
Um BOOST LM 



Fig. 1— Semi-adjustable electrostatic 
focus circuit in Crosley 472 chassis. 



FOR maximum screen brightness 
and picture detail, the electron 
beam of a cathode-ray tube must 
be brought to the sharpest pos- 
sible focus at its point of contact with 
the screen. Should the beam be too wide 
at this point the individual scanning 
lines overlap, producing a blurred and 
poorly focused picture (see photo). 

When electrons leave a heated cath- 
ode, they tend to spread out in a broad 
beam because they are like (negative) 
charges and thus repel each other. 
Through a system of lenses these elec- 
trons are accelerated and when they 
reach a high velocity are focused on 
the picture-tube screen — their momen- 
tum preventing them from spreading 
out. Higher anode voltages provide bet- 
ter focus; however, they must be lim- 
ited because they increase the deflection 
power necessary for scanning. 

The problem of focusing has been 
attacked two ways — -by the construc- 
tion of the picture-tube electron gun 
and by using external magnetic devices 
placed over the neck of the tube. The 
early television receivers containing 
10- to 16-inch picture tubes such as the 
popular 10BP4, 12LP4, 14BP4, 14CP4, 
16AP4, 16GP4 and 16KP4 used mag- 
netic focusing in which the electron- 
beam concentration was controlled by 
the magnetic field of a focus coil or 
permanent magnetic focus device. 

In recent years the low-voltage elec- 
trostatic-focus tube has been developed 
and is growing increasingly popular. 
This type — the 17HP4, 20HP4-A, 
21ALP4-A, 24DP4-A, etc. — requires no 
external magnet. Its beam is focused 
by an electrostatic field set up by a 
potential applied to a focusing electrode 
(pin 6). Another relatively new devel- 
opment is the automatic-focus type tube, 
such as the 20JP4, that needs no mag- 
netic focus field or focus voltage. While 
holding much promise, this type has not 
been widely used. 

The early focus coils were pretty 
much standardized. They were gener- 
ally 247-ohm 200-ma, 470-ohm 140-ma 
or 360-ohm 150-ma coils. Despite the 
increased use of permanent-magnet 
focusing devices, many manufacturers 
still use focus coils whose resistance, 

MAY, 195* 



depending upon circuitry, may be as 
high as 2,000 ohms. 

Focus control circuits 

Good focus is often a critical adjust- 
ment varying considerably among the 
same tube types. Changes in second- 
anode voltage will often necessitate 
focus readjustment. Interaction between 
the magnetic fields of the focus magnet 
and the deflection coil will also affect 
focus. Thus most sets provide for a 
wide range of focus control. 

A typical electrostatic focus control 
is shown in Fig. 1. It is used in the 
Crosley chassis 472. The focus electrode 
of the 21ATP4 low-voltage electrostatic 
picture tube may be connected to 
ground or to a potential of 150, 260 
or 490 volts. In installing or repair- 
ing this set each of the four connec- 
tions should be tried to obtain the 
sharpest picture or sharpest horizontal 
lines. Whenever the picture tube is 
replaced, all connections should again 
be tried. 

Fig. 2 shows the focus arrangement 
in the Admiral 23B1AZ chassis. Here 
the 24TP4 or a 24CP4-A picture tube 



TO HIGH Bf RECT 

10W B+ RECT 

5U4-G 



J50V 



l20 M f ^ 




picture tube is used in which the focus- 
electrode voltage is controlled by a 
potentiometer connected between 480 
volts and ground. The 2-megohm unit 
thus provides a continuously variable 
focus voltage, permitting a more pre- 
cise adjustment than in Fig. 1. 

One last circuit (Fig. 4) lest we 
become too complacent about focusing 
systems. This is found in the G-E model 



Fig. 2 — Continuously variable magnetic 
focus control in Admiral 23B1AZ sets. 

used requires magnetic focusing. A 
1,900-ohm focus coil is connected in 
series with parallel 7,500-ohm potenti- 
ometers between a B-plus voltage of 
approximately 150 and ground. Here 
again a wide range of focus is evident 
with the potentiometers ranging from 
zero resistance to approximately twice 
that of the focus coil. 

Fig. 3 shows the focus circuit of the 
Westinghouse V-2314 and V-2324 chas- 
sis. A 24DP4 or -A electrostatic-focus 




Fig. 3 — Westinghouse focus circuit. 
17C110 where the focus coil is in the 
cathode circuit of the 6W6-GT audio 
output tube. Here, a portion of the 
tube's plate and screen current passes 
through the focus coil, the amount 
determined by the setting of the 10,000- 
ohm focus control. 

Focus defects and adjustments 

The edges of a picture are usually 
not in perfect focus when the center is 

6W6-GT 

.008 AUDIO OUTPUT 
± 47a 



01 



IK 





' +1 

. 5 °1 


f I0K « 


;focus "4= 


3 FOCUS < 
§1 COIL 4 


>330a/IW 



Fig. 4 — Magnetic focus circuit used 
in several General Electric TV sets. 

53 



www.americanradiohistorv.com 



TELEVISION 



sharpest. This is a normal condition, 
provided the defocusing (astigmatism) 
is not excessive; it is common when the 
focus coil is used for centering or' cor- 
recting corner shadows. 

Focus circuits are relatively simple 
and easy to check. Where focus is poor 
and the control has little or no effect, 
check the focus coil for an open circuit 
or shorted turns. Also check the focus 
potentiometer and associated circuitry. 

The location of the focus coil or mag- 
net on the neck of the tube affects pic- 
ture centering. It should generally be 
placed about % inch behind the deflec- 
tion yoke — bringing it closer will pro- 
duce interaction between the magnetic 
fields of the two and cause poor focus. 
The coil provides a limited centering 
control and should be adjusted in con- 
junction with the ion-trap margnet, 
with the latter being used only to obtain 
maximum brightness — leave centering 
and shadow correction to the focus coil 
and centering magnet (after carefully 
adjusting the yoke). 

In cases of poor focus where the coil 
and control circuits have been checked 
out, replace the picture tube or check 
it for gas. 

The PM focus magnet (Focalizer) 
must be adjusted with a nonmagnetic 
screwdriver. It consists essentially of 
three or four small bar magnets in a 
frame encircling the neck of the tube. 
Magnet strength is controlled by a 
shorting screw that shunts the mag- 
netic field of the focus magnet that 
would ordinarily pass through the neck 
of the tube. Where a magnet is too 
strong, the technician can improvise a 
shunt to bring the unit to a point where 
it will provide optimum focus. 

When replacing a tube using a focus 
coil with an electrostatic-focus type, 
remove the coil from the neck of the 
tube and place it as far from the tube 
as the cabinet permits. Do not remove 
the coil from the circuit unless you 
replace it with a resistor of equivalent 
value and wattage. 

Changing Focalizer strength 

.4 customer complained her picture 
had a slight blur. The set couldn't be 
focused properly in the home so it was 
brought to the shop. We have tried a 
few Focalizers made by a well-known 
manufacturer and in each case, with 
the screw all the way in, the picture 
comes close to looking acceptable, but 
not quite. We have tried moving the 
magnet around slightly but that did 
not help. Since there is no other focus- 
ing control, we are at a loss as to the 
trouble. Does this set use some special 
focus magnet? And if so, why should 
the regular magnet suddenly become 
too strong? I can understand a magnet 
becoming weak. — S. C, Trenton, N. J. 

It is most improbable that the Focal- 
izer has increased in strength. More 
likely a change has taken place in the 
physical characteristics of the picture 
tube. If you have not already done 
so, try replacing the tube — the old xme 

54 



may be slightly gassy. Also try read- 
justing the deflection yoke firmly 
against the flare of the tube and adjust 
the ion-trap magnet for maximum 
brightness. 

If these do npt help, the strength of 
the Focalizer can be reduced by the 
following: Take a piece of 1/16-inch 
steel, approximately l 1 /^ inches square. 
Round it so that it matches the curva- 
ture of the focus magnet and place it 
anywhere on the circumference of the 
magnet so that it covers a portion of 
the air gap. The steel shunt will be 
held firmly in place by the magnetic 
attraction of the Focalizer and will 
reduce the strength of the unit to a 
point where optimum focus can be 
obtained. 

Vertical nonlineari+y 

A Crosley model H-17TOBH has 
come in with a very bad case of vertical 
nonUnearity at the top of the picture. 
Adjusting the vertical linearity and 
height controls does not improve the 
picture. Every component related to the 
vertical oscillator and output stages has 
been checked and appears O.K. In 
replacing the 12BH7 I noted some 
improvement, but nowhere near ivhat 
the picture should look like. 

I have a schematic of the set and all 
connections are as they should be. The 
picture is very clear and steady, but 
just not linear. What next? — /. S., 
Cranston, R. I. 

You omitted an important piece of 
information — is the top of the picture 
spread or compressed? They have dif- 
ferent solutions. This trouble goes 
beyond your set and is fairly common 
in most of the Super V series. Try 
several 12BH7's. If this does not help, 
replace the vertical output transformer 
and again try a few 12BH7's. Very 
often some particular combination of 
these components will produce non- 
linearity and changing them will cure 
the trouble. 

If the above does not help, spread- 
ing can usually be corrected by insert- 
ing a peaking circuit consisting of an 
.01-^f 600-volt capacitor in series with 
a 150,000-ohm 1-watt resistor, con- 
nected from plate to ground of the 
vertical output stage (Fig. 5). In some 



150K .01 1/2 12BH7 
• — %W — 

SEE TEXT 



fT OUTPUT TRANS 
VERT BER COLS 




Fig. 5 — Crosley vertical output circuit 
with components added to correct non- 
linearity at top of the picture. 



cases the fixed cathode resistor should 
be increased in value slightly to about 
7,500 ohms, also 3 watts. These compo- 
nents affect the current waveshape in 
the yoke so as to add a slight amount 
of compensating spread. 

If the top of the picture is com- 
pressed, add a resistor of about 68,000 
ohms between the grid of the vertical 
output tube and the ,047-^f capacitor. 
This resistance will spread the input 
waveshape fed to the output stage so 
as to compensate for the compression. 

Make a record in the cabinet of what 
you have done — changing the 12BH7 or 
vertical output transformer in the 
future may require that the compen- 
sating networks be altered or elimi- 
nated. 

Tracking 

An RCA set with a KRK-7 tuner 
has come in with a complaint of poor 
picture and sound. It could be cleared 
by fine tuning but the set would drift 
considerably. The rf oscillator was 
replaced and this took care of the 
drifting. However, the tracking was 
very bad. I tried to align the set but 
this did not help. Is there any special 
alignment procedure so that the set 
will track properly? All rf and if tubes 
have been replaced and all voltages 
appear normal. I made a thorough 
check of all connections in the tuner 
and have cleaned all contacts. — J, W. y 
Ogden, Utah 

Oscillator-tube characteristics vary 
considerably and you should try several 
of them before doing anything else. If 
this does not help and you are reason- 
ably certain that the set is in good 
operating condition otherwise, there is 
a solution that is fairly popular. 

Run a continuous length of tinned 
copper bus wire from eyelet to eyelet of 
the high-channel inductance strap on 
the rear section of the oscillator wafer 
switch. The wire between the eyelets 
should be in the form of small semi- 
circles having a length of about 7/16 
inch and laid flat against the inductance 
strap. Solder each contact with the eye- 
let and make sure it is mechanically 
firm. Some time ago RCA made a rec- 
ommendation similar to this and sug- 
gested No. 20 wire be used. However, 
good results could also be obtained 
with No. 22 wire. 

In making the tracking adjustment, 
the semicircular loop should be moved 
slightly away from the inductance 
strap and the oscillator channel adjust- 
ment screw turned until the screw is 
in the center of its tuning range. When 
the wire is against the strap, there is 
practically no change from the original 
tracking. If necessary, the method may 
be applied to the high-channel rf and 
converter circuits. end 

All queries to the TV Service Clinic should be 
accompanied by a stamped, self-addressed en- 
velope. This will insure a more rapid answer. 
Be especially careful to state the model or chassis 
number. In many cases these have been confused 
with the serial number which, in most cases, 
is meaningless. An unidentified receiver can be 
analyzed in general terms only. 

RADIO-ELECTRONICS 



www.americanradiohistorv.com 



AUDIO— HIGH FIDELITY 



DRIVER EMITTER RESISTOF 



W*. CLASS 





for TRANSISTORS 

An excellent low-distortion audio output stage 



100-n., 

UNUSED TAP ON OUT.PUJ TRAN 




Resistors and wiring 
on underside. 



By EDWIN BOHR 



WOULD you like to build a 
transistorized intercom, pho- 
no amplifier or power out- 
put stage? The class-B cir- 
cuit to be described is ideal for any of 
these purposes. It is exceedingly easy 
to construct and the performance, as 
will be explained in detail, excels most 
commercial circuits. Important, too — 
all components are readily available! 

For audio operation class B offers all 
the advantages. The power-handling 
capabilities of the transistor are used 
to the fullest, efficiency is amazingly 
high and distortion can be kept below 
2%. This distortion figure, incidentally, 
is better than most battery-operated 
vacuum-tube circuits can obtain. 

Dollar-variety transistors operate 
successfully in this circuit to 100 milli- 
watts. If it is really necessary they 
can be pushed to *4 watt. 

The class-B circuit 

Using push-pull operation, this bridge 
circuit (Fig. 1 ) is a refinement meet- 
ing wide acceptance in the design of 
all types of new audio equipment. It is 
particularly advantageous, however, for 
class-B operation. 

Ordinarily much of the distortion in 
a class-B stage results from an im- 
perfect output transformer. Since the 
bridge circuit can either drive a voice 
coil directly or use a single-primary 
output transformer, these troubles are 
largely eliminated. 



3 PNP TRANSISTORS 

CK722,2NI07 

OR EQUIV 



That is why most commercial tran- 
sistor output stages use the bridge 
circuit. However, virtually all these 
circuits employ a special split-secondary 
driver transformer not commercially 
available. A few people with trans- 
former-winding facilities have built and 
used such a circuit but, for the indi- 
vidual with no special facilities, it has 
been out of reach. 

The circuit presented here can be 
built by anyone. After much searching, 
a nationally advertised transformer 
has been found that is just about ideal 
as a driver for the bridge type of push- 
pull output stage. The transformer 
does require a slight modification, but 
this is very simple and requires only 
peeling back the outer paper wrap 
from one side. 

Distortion 

Before going further into the actual 
circuit let's look at a peculiar, but 
very interesting, aspect of transistor 
class-B operation. 

Curve A of Fig. 2 shows the distor- 
tion of a typical class-B transistor 
stage increases at near maximum out- 
put and at very low output levels. But, 
the distortion is most severe at low 
output. 

Distortion at high output is common. 
But why does it increase so drastically 
at low levels? The answer is simple. 

For very small driving signals the 
transistor, input resistance is very non- 




linear. In fact, below a certain thresh- 
old voltage the transistor does not 
respond appreciably to any input signal. 
Commercial circuits overcome this diffi- 
culty with a bias current to lift the 
transistor out of its nonlinear region. 
The bias reduces the low-level distor- 
tion (curve B, Fig. 2) but it also in- 
creases medium-power distortion, places 
a fixed bleeder current on the power 
supply and lowers the maximum power 
capacity of the transistors since the 
bias causes transistor heating. 

Fig. 1 does not use bias to reduce 
low-level distortion; negative feedback 
is used instead. Feedback does not huve 




Fig. 1 — Schematic of class-B output stage for 100- or 200-mw operation. 
MAY, 1956 



"0 10 20 30 40 50 60 70 60 90 100 110 
% RATED POWER OUTPUT 

Fig. 2 — Diagram shows typical dis- 
tortion curves for class-B stage. 

the power- wasting and other undesir- 
able effects of the bias system. Further- 
more, feedback reduces distortion at all 
power levels and smooths out the fre- 
quency response curve. 

Fig. 3-a indicates the no-bias, low- 
output distortion of a sine wave. Fig. 
3-b shows the improvement when feed- 
back is added. Both photos present the 
distortion at its worst. The slight gap 
in the photograph with feedback is a 
result of high-frequency ringing at the 
zero-crossing point. This effect is com- 
pletely eliminated in the finished circuit 
and there is no perceptible distortion 
up to the rated output. 

Fig. 4 shows the overall response of 
the driver and class-B output stage. 
Low-frequency response is limited by 
transformer overloading. The high- 
frequency response is deliberately rolled 
off to prevent the ringing just men- 
tioned. Considering that two small 
transformers are used in the circuit, the 
response is very good. 

Efficiency is so high that in some 

55 



www.americanradiohistorv.com 



AUDIO — HIGH FIDELITY 



DRIVER TRANS 
OUTPUT STAGE 



DRIVER 



OUTPUT TRANS 



Left — Fig. 3 — C 
show reducCi 
distortion 
feedback is a 
Right — View shows 
ment of compo 




applications it may be unnecessary to 
include an on-off switch. With no audio 
input the amplifier draws an idling- 
current of only 1 ma. And most of this 
is consumed by the class-A driver. 

When an audio signal is applied, the 
amount of current drawn depends on 
the signal amplitude. With loud sig- 
nals the current may climb to 20 ma. 

For these reasons the circuit is very 
attractive for intercoms or other appli- 
cations where the amplifier sits idle for 
long periods. 

Construction 

Terminal cards (see photo) are the 
ideal medium for transistor circuit 
construction. The three major com- 
ponents are the two transformers and 
the 160-^f electrolytic capacitor. The 
electrolytic need not be so large; any 
5-^f, or higher, capacitor rated for 3 
volts or more should be satisfactory. 

The output transformer has a tap 
for either 100- or 200-mw operation. 
The battery voltage, emitter resistor 
and shunt capacitor across the output 
transformer are changed when opera- 
tion is switched from one power to the 
other. The shunt capacitor is essential 
for proper operation; it is not ginger- 
bread work. 

The transistors are soldered directly 
to terminal lugs. Possible transistor 
damage from soldering may have been 
somewhat exaggerated. Transistors can 
even be dip-soldered into place. If the 
transistor is soldered quickly (this is 
the really important thing), no pliers 
or other heat sink is necessary. But, 
if you are in doubt, use the pliers. 

Feedback is supplied to the driver 
through the 100- and 10-ohm resistor 
combination. For this reason the driver 
input must be applied between ter- 
minals 1 and 2. Typical inputs for both 
transformer and R-C coupling are 
shown on the diagram. 

The driver transformer modification 
is really very simple but it requires a 
little thought and common sense. The 
transformer is an Argonne AR-109 
sold by Lafayette Radio. A data sheet 
supplied with it indicates the start and 

56 



finish of + he windings along with the 
color coding of the wires. This same 
nomenclature is followed in Fig. 1. Not 
all transformers have the same color 
wire for the secondary center tap. On 
this unit it was black. 

The modification separates the center- 
tapped secondary so the two halves 
become independent windings. To do 
this, slit open the outer paper wrap, 
exposing the center tap and its connec- 
tion to the external lead wire. Cut 
apart the center tap. An external lead 
wire is then soldered to the free end 
produced by the cut. I used a white 
lead as labeled on the diagram. 

This wire must be small and flexible. 
If none is available, excess lead from 
the same transformer can be used. 

The leads can be pressed into place 
and held with a few drops of hot wax. 
Also, the wrap can be pushed into the 
warm wax and resealed. When this is 
done, check off and pair the secondary 
wires with an ohm meter. A pair goes 
to each transistor — one wire to the 
base, the other to the emitter. They 
must be connected exactly as the dia- 
gram shows. Before connecting, check 
to see that there is no continuity be- 
tween the two secondary halves. 

Circuit operation 

This is a basic output circuit. It can 
be driven by either a preceding tran- 
sistor stage or matching transformer. 
The input impedance is in the neighbor- 
hood of 3,000 ohms. And, if a low-gain 
transistor is used for the driver, 200 
mv of signal produces full output. 
High-gain transistors, of course, require 
less signal. The circuit can be pushed 
to 0.25- watt output by increasing the 



Parts for class-B circuit 

! — 10, I — 100, I — 6, BOO (or 12,000) ohms, '/ 2 -watt re- 
sistors; I— 0.1- (or 0.25-) uf capacitor, 200 volts, 
miniature; I — 160-uf 6-volt electrolytic capacitor; 
3— p-n-p transistors (CK722. 2NI07, etc.); I— driver 
transformer, primary impedance 10,000 ohms, sec- 
ondary 2,000 ohms ct; primary resistance 500 ohms 
secondary 50 ohms (Argonne AR-109 or equivalent); 

1— output transformer, primary impedance 500 ohms 
ct, secondary 3.2 ohms; primary resistance 20 ohms, 
secondary 0.3 ohms (Argonne AR-II9 or equivalent); 

2 — 6-volt batteries; I — insulated mounting board- 
mounting pins. 



batteries to 16.5 volts while retaining 
the 200-mw circuit values. 

Check voltages are shown on the 
diagram. These are based on 100-mw 
operation with no signal. Operation is 
normal if the meter readings are within 
one-half to twice these values. 

Because the AR-109 has low winding 
resistance, the base-to-emitter resist- 
ance is low enough to obviate the usual 
stabilization resistors. 

To read the current with the signal 
applied, place a milliammeter in either 
of the battery leads. A milliammeter 
placed in the common lead indicates 
how well the output transistors are 



100^ IKC 10 15 20 

FREQ 

Fig. 4 — Response of the class-B stage. 

matched. A current here of more than 
3 ma at full signal indicates poor match- 
ing. They should be as nearly alike in 
characteristics as possible. 

Most p-n-p transistors are suitable — 
for example, the CK722. Do not use 
types that have low power and collector- 
voltage ratings. Several companies offer 
matched pairs of transistors for class 
B, I certainly recommend these be used 
if the pocketbook can take the extra 
pinch. 

Occasionally, this amplifier will oscil- 
late at near-ultrasonic frequencies, pro- 
ducing distortion. This can be cured by 
spacing the input and output wires, 
grounding the circuit or placing 10,000- 
ohm resistors between collector and 
base of the output transistors. end 

(There is some feeling among author- 
ities in this field that it may be ex- 
tremely difficult to obtain an output 
of 200 mw using CK722's or 2N107's in 
this circuit. High-current transistors 
are needed for appreciable output. 
Perhaps the added cost of matched 
2N109's or Amperex OC72's will be 
justified by the large increase in power 
output. — Editor) 

RADIO- ELECTRONICS 



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THE 

Flux 


;valve 






PICKUP 



AUDIO— HIGH FIDELITY 



MAGNET 



POLE PIECES 
/( STYLUS 

Afl MATURE 



PIVOT 




Higher compliance and lower 
vibratory mass ??iake for 
superior pe?'formance 

By W. O. STANTON* 



/ 

POLE PIECE 



Fig. 1 — Phantom view 
of the Flux valve 
pickup. The ends of 
the pivot wire, shown 
straight for clarity, 
are actually bent over, 
as shown in Fig. 2. 



FOR pickup performance on contem- 
porary records approaching close- 
ly to the ideal, we need a consider- 
ably higher level of mechanical 
refinement than has been standard in 
the past and, in particular, a much 
higher compliance and lower vibratory 
mass. But the desirable compliance 
and the mass values have always been 
extremely difficult to combine with the 
ruggedness and ease of stylus replace- 
ment that pickup users today rightfully 
expect in a high-quality instrument. 

I will describe in this article a new 
pickup in which all of these mechanical 
characteristics have been combined to 
open up a radically higher level of 
reproduction from disc recordings. The 
tough mechanical design problems have 
been licked by putting the whole vibra- 
tory system, including the stylus, in a 
small plastic-encased insert, which the 
user can put into or remove from the 
pickup without using tools of any kind. 

Magnetic circuit 

The way the pickup operates can be 
made clear by a description of the mag- 
netic circuit. When the insert is in 
place, the stylus projects parallel to a 
lip in the plastic pickup housing, as 
can be seen in Fig. 1 and the photo. 
The magnetic flux — produced by the 
permanent magnet enclosed in the pick- 
up housing — is carried by a metallic 
member out through the housing to a 
point directly above the top or butt 
end of the stylus. There an exposed 

* President, Pickering & Co., Inc. 
MAY, 1956 



metal button contacts a similar button 
on the insert. 

The button on the insert is the top 
end of an inverted metal cup, which 
surrounds the upper end of the stylus, 
leaving it free to move. This cup can be 
seen in dotted lines at the butt end of 
the stylus in Fig. 2. It carries the 
magnetic flux to the stylus tube itself. 
In the lip of the pickup housing directly 
in back of the lower end of the stylus 
are the ends of two metallic members, 
side by side, centered on the line through 
the resting position of the stylus. These 



carry the magnetic flux back into the 
housing and through the coil. 

The magnetic circuit is so arranged 
that when the stylus is in its center 
position, not moving, flux flows from 
it equally to the two members behind 
its tip and the two lines of flux balance 
each other out so that no voltage is 
produced in the coil. W^en the stylus 
moves to right or left, One side gets 
more flux than the other, the magnetic 
circuit is unbalanced and flux flows 
through the coil, producing a signal 
voltage. 




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AUDIO— HIGH FIDELITY 



Mechanical vibratory system 

As shown in Fig. 2 and the photo of 
the insert, the stylus projects through 
a hole in the center leg of the insert. 
The stylus is attached to a wire that 
runs along the longitudinal axis of the 
insert and moves to follow the record 
modulation by bending this wire. The 
wire is held mainly at its two ends, 
which are bent to hold it firmly in the 
insert. 

The lateral compliance of the stylus 
with this suspension system can be 
made extremely high by proper choice 
of the wire material and thickness. In 
the present pickup the compliance has 
been raised as high as it can be with- 
out leading to off-center motion, even 
in the most refined pickup arms. The 
compliance of this pickup is too high 
for use with some record changers and 
the pickup is not recommended for all 
such applications. A manually operated 
arm of very low friction and highest 
quality is desirable. 

The proper amount of vertical com- 
pliance is included to allow stylus 
motion through " pinch" effects and 
record irregularities such as may occur 
in normal record pressings. The value 
of vertical compliance chosen is such 
that the stylus can respond to vertical 
forces without losing contact with the 
record groove even under conditions 
of high transient groove modulation. 

Vibratory mass 

The stylus and its tube comprise 
the whole vibratory mass, so that this 
mass is unprecedentedly low. As a 
consequence, the armature resonance of 
the pickup is far above the audible 
frequency spectrum, in the neighbor- 
hood of 30 kc. This greatly improves 
the performance of the pickup at high 
frequencies and gives it excellent ability 
to handle transient signals, which are 
highly sensitive to any abrupt change 
in the mechanical response character- 
istics in or near the operating frequency 
band. The lack of a peak in the operat- 
ing range also eliminates the distortion 
that such a peak can produce in sub- 
harmonics of the resonant frequency. 
A strong peak at 10,000 cycles, for 



instance, will increase the distortion 
at 5,000 and 2,500 cycles. 

Nothing contributes so much to 
clarity, snap, smoothness, listening ease 
and low surface noise as low moving 
mass and the absence of peaks within 
the operating frequency range. 

The entire pickup, including the 
magnet, coil and magnetic gap, is com- 
pletely encapsulated in a tough plastic 
v/hich practically guarantees it an end- 
less life. The encapsulated parts can- 
not be damaged in any way, short of 
a coil burnout by application of a heavy 
dc voltage to the pickup terminals (a 
theoretical disaster which is extremely 
improbable). The only parts which 
move and wear are in the insert and 
so, when the user puts in a new insert, 
he is getting in effect a whole new 
pickup. 

Electrical characteristics 

The output of the pickup is about 
25 millivolts at the normal recording 
level of about 10-15 centimeters per 
second. The frequency response is 
absolutely Mat well beyond both ends 
of the audible frequency spectrum. The 
value of this superaudible response at 
the high end has ah^eady been noted. 
It insures smoothness and excellent 
handling of transients. Intermodulation 
distortion has been reduced to a neg- 
ligible level by careful arrangement of 
the magnetic circuit. The impedance of 
the pickup is medium high. It should 
work into a load of about 27,000 ohms. 

Effect on record wear 

The very high lateral compliance, the 
small mass and the lack of any mechan- 
ical resonance in the operating range 
combine to produce an additional ben- 
efit. With a stylus in good condition 
and in a well-designed arm which lacks 
strong arm resonances, the pickup does 
not tend to wipe off the record the 
microscopic groove modulations repre- 
senting the highest frequencies, which 
is the fixed habit of pickups with heavy 
moving systems and mechanical res- 
onances in the mid-high frequency 
range. Record wear, in other words, 
has been reduced to a new, much lower 



level. Records played with the pickup 
will keep their top "sheen" indefinitely 
and exhibit no increase in the level of 
surface noise. 

Mounting system, stylus force 

The pickup is supplied with a mount- 
ing clip which also forms the bearing 
for pickup rotation. The clip has mount- 
ing holes on standard (RETMA) V 2 - 
inch centers and can be attached to 
almost any of the high-quality arms 
available on the market. 

Because of the extremely high lateral 
compliance and low mass, the pickup 
will track with a vertical stylus force 
as low as 3 to 5 grams, depending 
somewhat on the character of the record 
modulation. With reasonably flat rec- 
ords, not modulated at an abnormally 
high level, and with a well-leveled turn- 
table (see below), the lower figure of 
3 grams is enough for perfect tracking. 

Turntable leveling 

To get the full benefit of the high 
lateral compliance of the pickup, it 
should be used on a turntable that has 
been dynamically leveled. This means 
that, under operating conditions, with 
the record exerting a dragging force 
on the stylus, the arm has no tendency 
to push toward either the inside or out- 
side of the record. 

To find the turntable position w T hich 
produces this neutral condition of the 
arm, put on the table a blank record, 
such as an unused recording blank. 
Start the motor and put the pickup 
down on the moving record surface. 
Then level the turntable so the stylus 
does not move toward either the out- 
side or the inside of the record. In this 
position, the arm will be climbing very 
slightly "uphill" in its travel from out- 
side to inside of the record, and the 
force of gravity tending to slide it back 
toward the outside will closely offset 
the pull of the groove friction, which 
tends to pull the arm toward the inside. 
With a neutral arm, the high compli- 
ance of the pickup will produce the 
maximum of faithfulness to the groove 
and thus the maximum clarity of repro- 
duction. END 




www.americanradiohistorv.com 



AUDIO— HIGH FIDELITY 




ll 



Tl 

JJJI 




One of a series of articles 
on modern audio equipment, 
Power output and driver 
circuits are discussed here 



POWER AMPLIFIERS 

By JOSEPH MARSHALL 



THE high quality of performance of 
modern high- fidelity equipment is 
due in large part to highly spe- 
cialized and sometimes unique cir- 
cuitry. The service technician who 
looks for the first time at the wiring 
diagrams of modern commercial hi-fi 
equipment is very likely to be puzzled 
and perhaps even shocked by some 
highly unorthodox and unfamiliar cir- 
cuits. High-fidelity circuits can be 
divided into two general categories: 
those applying to power amplifiers; 
those applying to control units, pre- 
amplifiers and accessories. 

Power amplifiers consist of three 
sections: the power output stage whose 
function is to deliver to the speakers 
anywhere from 10 to 50 watts of power 
with minimum distortion; the driver 
which must supply sufficient driving 
voltage to the output stage to drive it 
to maximum output; a phase inverter 
to convert a single-ended input signal 
to a push-pull signal, since almost all 
power amplifiers in high-fidelity equip- 
ment use push-pull parameters or an 
equivalent. 

The classic power output circuit is 
shown in Fig. 1. Two triodes or pen- 
todes are arranged with plates loaded 
and grids driven in push-pull. (Beam- 
power tetrodes are classed as pentodes 

* From the book Maintaining Hi-Fi Equipment, 
Gernsback Library. 




Fig. 1 — The basic push-pull amplifier. 
MAY, 1956 



in this article.) In older, inexpensive 
high-fidelity amplifiers^ the circuit usu- 
ally has 6V6 tubes as pentodes. 

it is not easy to obtain high-power 
outputs with receiving type tubes. One 
of the first steps in the rapid progress 
of high-fidelity design in the past decade 
was the use of transmitting types in the 
output stages. There were two reasons 
for this: 

First, these transmitting tubes re- 
quire very little driving voltage even 
when used as triodes. Thus, where the 
6B4 family requires 60 volts peak per 
grid of drive, transmitting pentodes of 



the 807 family used as triodes require 
only 40 volts. 

Theoretically it should easily be pos- 
sible to design drivers capable of de- 
livering 60 volts peak with low distor- 
tion. In practice it is difficult to do so 
without increasing distortion to high 
levels. But 40 volts is easily supplied 
and at a distortion level very much 
lower. 

Second, where receiving type tubes 
have to be driven into nonlinear opera- 
tion to deliver 10 or 15 watts of output, 
transmitting tubes deliver this output 
over the most linear portion of their 



R2-5.IK APPR0X (VALUE TO BE CHOSEN FOR 20 DB FEEDBACK) 



PWR OUTPUT 



6SN7-GTA 

DRIVER 



33K /2W 




5U4-G 




± 40 ± 



TO KT66 CATHODES 



Fig. 2 — Craftsmen C-500, typical Williamson amplifier using triodes. 



59 



www.americanradiohistorv.com 



AUDIO— HIGH FIDELITY 



curves, operating at only a small frac- 
tion of their maximum capabilities and 
strictly class A. Thus, distortion can 
be reduced to a small fraction of that 
with receiving type tubes. By this time 
it had become very clear that low distor- 
tion was the primary consideration and 
that a wide bandwidth was tolerable 
only when distortion was reduced to 
insignificant levels. The use of trans- 
mitting tubes provided a simple means 
of obtaining the desired Jow distortion. 

The Williamson amplifier 

This trend found its most notable 
expression in the amplifier named after 
D. T. N. Williamson, engineer of the 
British firm, Ferranti. The Williamson 
circuit not only used transmitting type 
tubes, but used them with highly refined 
circuitry for drivers and inverters. It 
was one of the most successful audio 
designs in electronic history. Even 
now, most commercial amplifiers use 
either some modification of the William- 
son circuit or portions of it. 

There is nothing very remarkable 
about the circuit. The original used 
two transmitting pentodes connected as 
triodes and loaded with an output trans- 
former of hitherto unprecedented band- 
width, low distortion and very large 
size. The biasing arrangement was 
complex but permitted excellent balance 
and precise bias adjustment. The 
first amplifier-inverter used direct cou- 
pling to minimize phase shift at the 
low-frequency end. (See Fig. 2.) 

A number of improvements were 
made as the circuit was applied to 
commercial equipment. One modifica- 
tion is that of splitting the self-bias 
resistors of the output tubes. About 
half the bias for each tube is developed 
in an independent unbypassed cathode 



resistor. This provides some current 
feedback to reduce distortion further. 

As output transformers were im- 
proved and bandwidth extended to 100,- 
000 cycles and beyond, it became more 
difficult to maintain stability in the 
feedback loop at the extremes, par- 
ticularly at the resonant peak of the 
output transformer which fell usually 
in the region around 100 kc. One expe- 
dient was to include within the loop, a 
bypass network affecting only the fre- 
quencies around and above 100 kc. This 
took the form of a resistor and a 
capacitor in series (Rl and Cl, Fig. 2) 
in the plate circuit of the input tube 
which bypassed the unwanted ringing 
frequency. To minimize these troubles 
further, a phase-shifting capacitor (C2) 
was added in parallel with the feedback 
resistor. This network had a time con- 
stant which produced a phase shift 
opposite to that of the output trans- 
former at the ringing frequency, or in 
that region, 

Ultra-Linear operation 

About 1952 David Hafler and Herb 
Keroes revived an unusual output tube 
circuit which had been patented some 
years before and which provided opera- 
tion combining the best features of 
triode and tetrode or pentode operation. 
This Ultra-Linear configuration made 
only a very slight change in the normal 
push-pull circuit; the screen grids were 
connected to taps on the primary of the 
output transformer. There is some 
controversy about how this circuit 
actually operates but the general con- 
sensus is that connecting the screens in 
this way applies a certain amount of 
negative feedback. 

In any event, the connection has some 
very great virtues. First, the operating 



ftf TO PREAMPL 



607orKT66(2) 




** J 



I fc>sv/3* 5V4-G 

&-200MA f ■ 17V 

B re /- 1 



IO±500WV±IO 2fl±4 



C 6.3V 



Fig. 3 — Typical Williamson amplifier designed for Ultra-Linear operation. 



60 



curve is more linear than that of either 
triode or pentode operation. Second, 
the power output capabilities are about 
one-half those of pentode connection 
and about double those of the triode 
connection. Thus, with the same plate 
supply voltage and drive, the Ultra- 
Linear configuration doubles the output 
power over that of the triode William- 
son. More important than this is the 
fact that distortion is decreased at low 
output levels. Finally, the tube capac- 
itances are the same as in pentode 
operation. This eliminates, or at least 
greatly minimizes, the Miller effect at 
high frequencies. It not only makes 
possible an upward extension of the 
bandwidth, but — more important — re- 
duces the phase shift in the region of 
100 kc. It therefore permits the use of 
larger feedback factors for an equal 
degree of ringing. 

The Ultra-Linear circuit was imme- 
diately applied to the Williamson design 
and a high proportion of today's com- 
mercial amplifiers are Ultra-Linear 
versions of the Williamson. A typical 
circuit is shown in Fig. 3. 

Cathode loading 

Meanwhile, considerable work was 
being done on cathode loading of power- 
output tubes. It was known that such 
loading produced high power with very 
low distortion, since cathode loading 
results in current feedback. Cathode 
loading also improves the high-fre- 
quency response greatly. This permits 
higher feedback with less risk of ring- 
ing or instability at the transformer 
resonant frequency. Unfortunately, 
cathode followers have no voltage gain; 
hence the drivers have to supply some- 
where between 150 and 200 volts of 
drive per side. This is a serious problem 



TO *>LTAGE AM PL CATH 




T460V 
"325V 

Fig. 4 — Cathode-loaded output circuit. 

FROM DRIVER 



- f) [,..; 

Fig. 5 — Output circuit shows Ultra- 
Linear design with cathode loading. 

RADIO-ELECTRONICS 





www.americanradiohistorv.com 



AUDIO — HIGH FIDELITY 



since, as mentioned before, it is difficult 
enough to supply 60 volts of drive with 
low distortion. 

Though complete cathode loading 
poses too many problems, it was quickly 
perceived that partial cathode loading 
would provide a good degree of current 
feedback without raising the driving 
requirements out of practical reach. 
Several circuits of this type were devel- 
oped, differing in the ratio of plate-to- 
cathode loading. Typical examples are 
the British Quad amplifier and the 
American Bogen DB15G. (A simplified 
circuit is shown in Fig. 4.) 

Both of these use pentode operation, 
obtaining a low output impedance by 
combining current feedback via the 
partial cathode loading and voltage 
feedback of an overall loop. Since pen- 
todes are far more sensitive than 
triodes, a simpler driver can be used. 
The Bogen uses merely the first two 
stages of the Williamson front end; 
the Quad uses a pair of pentodes in the 
paraphase phase-inverting circuit. 

It is possible to combine the Ultra- 
Linear configuration with partial cath- 
ode loading and this was done in the 
Fisher 70 A (Fig. 5) amplifier. 

An arrangement which looks rather 
similar is that of the Mcintosh ampli- 
fiers. (See "Circuit Features of High- 
Fidelity Power Amplifiers," August, 
1955.) In this, bifilar windings are 
used for the plate and cathode portions 
of the transformer primary and the 
screens are cross-coupled to the opposite 
plates. This arrangement permits class- 
ic operation with very low distortion 
and without the switching transients 
normally produced by such operation. 
Thus a pair of 6V6's can deliver out- 
puts in excess of 20 watts. Fig. 6 shows 
a simplified version of the output of 
the Mcintosh amplifier. 

I mentioned switching transients in 
the preceding paragraph. These occur 
when output tubes are driven to and 
beyond cutoff. The transient is pro- 
duced by leakage reactance of the out- 
put transformer which results in col- 
lapsing currents at the cutoff point and 
produces parasitic oscillation, audible 
in the output as a very annoying thump, 
which tears up the signal. Because these 
transients occur at cutoff or beyond, 
high-fidelity power stages avoided such 
operation. That meant, in practice, 
they were limited to class- A or -AB, 
operation. Unfortunately, this opera- 
tion is inefficient and it is difficult to 
obtain high-power output with it. Much 
design thought has therefore been 
expended on means of obtaining class- 
AB> or -B operation without switching 
transients. 

Before going into that we might men- 
tion two expedients for obtaining high- 
power outputs with class-A operation. 
One is a style of operation called A 2 . 
In this the tubes are never cut off but 
they are driven into the grid-current 
region. This produces higher distor- 
tion, but its effects can be minimized 
by careful balancing and high feedback 
factors. 



The first commercial amplifier to 
employ this mode of operation was the 
Brook unit designed by Lincoln Walsh 
which was the first great postwar high- 
fidelity amplifier. It has since been 
used also in the Fisher Laboratory 
model 50A. In this type of operation 
the grids draw considerable current, 
consequently the grid impedance must 
be very low. The driver is therefore a 
cathode follower with transformer cou- 
pling to the output tubes; even the low 
resistance of a cathode follower with 
resistor loads would be too great for A 2 
operation. The transformer also has 
capacitor coupling to extend the low- 
frequency response. This results in 
something intermediate between trans- 
former and double-impedance coupling 
(Fig. 7). 

Another possible arrangement (Fig. 
8) , not used at present in a commercial 
amplifier, is extended class-A operation. 
Here four identical tubes are used, one 
pair operating as triodes, the other as 
pentodes. At low levels the pentodes 
are cut off and do not contribute any- 
thing. At a certain point in the dynamic 
range, however, as the driving voltage 
increases and reduces the effective bias, 



FROM DRIVER 



ikj \ / Ool 








r y 


o 


^> OUTPUT 
B + 






°i 







Fig. 6- 



O BIFILAR PRIMARIES 

-Mcintosh output circuit. 

PWR AMPL 




Fig. 7 — Circuit for class-A, operation. 



Fig. 8 — Circuit 
for extended 
class A. 





Fi ff . 9 — Output 
circuit with plate 
of one tube and 
cathode of other 
loaded. 



MAY, 



9 5 6 



61 



.com 



AUDIO— HIGH FIDELITY 



OUTPUT STAGE I ^qv 



SEVERAL TUBES IN PARALLEL 
(if* 





Fig. 10 — Single-ended push-pull output. 



they begin to contribute and at max- 
imum output are the dominant devel- 
opers of power. Operation is class A, 
but the amplifier output power is much 
higher. 

One of the possible ways of using 
two tubes in a power stage is to load 
the cathode of one and the plate of the 
other tube. This appears in different 
forms in two commercial amplifiers: 
the National Unity-Coupled Horizon 
and the Electro-Voice Circlotron. 

Since the circuit diagrams of these 
amplifiers do not make the operation 
clear, let us examine the circuit in 
simplified form. The general idea is 
expressed in the simple diagram of Fig. 
9-a. Here we have, in effect, two tubes 
whose outputs are in series but whose 
inputs are in push-pull. The trans- 
former is connected in the middle of the 
circuit at the point where the two tubes 
are connected in series. It is in the 
plate circuit of the lower tube, in the 
cathode circuit of the upper one. Push- 
pull operation results because the two 
grids are fed by out-of-phase voltages 
and therefore, as the plate current of 
one tube rises, the current of the other 
falls. The load for both sections is 
common, so all the distortion products 
cancel. 

National and Electro-Voice have 
traveled two different paths to obtain 
a practical amplifier with this configu- 
ration. Electro-Voice turns the circuit 
into a bridge as indicated in Fig. 9-b. 
This requires two power supplies (indi- 
cated by batteries), but as long as the 
bridge is well balanced no dc can flow 
through the output transformer. This 
simplifies the design of a good output 
transformer; it also makes possible 
class-AB> operation approaching class 
B without switching transients. This 
in turn makes it possible to develop 
high power outputs with high efficiency. 
Triodes or pentodes can be used and, 
since the output impedance is very low, 
pentode operation in this mode produces 
as good or better damping factors than 
triode operation in conventional push- 
pull stages. Furthermore, the load 
resistance required is only one-fourth 
that required in plate loading. This 
makes the problem of producing a high- 
quality transformer considerably sim- 
pler. 

Since the output stage has no gain, 



high driving voltages are required. To 
obtain them a "bootstrap" driver cir- 
cuit has been developed. In this circuit 
(Fig. 9-b) the plate loads of the drivers 
are returned to the plates of the oppo- 
site output tubes. Their signal voltages 
add to the dc potential applied to the 
driver plates, effectively raising their 
plate supply voltage. 

National avoids the need for two 
high-current power supplies by arrang- 
ing the circuit as in Fig. 9-c. The out- 
put transformer has two primaries with 
unity coupling. One is connected in the 
plate circuit of one tube and the other 
in the cathode circuit of the other tube. 
The output tubes' screen grid and pow- 
er-supply filter capacitor improve the 
coupling between plate and cathode 
windings. Not as much drive is re- 
quired in this circuit and the preceding 
amplifier is simplified, consisting of a 
single twin-triode. For a more detailed 
discussion of this circuit, see "Circuit 
Features in Hi-Fi Power Amplifiers," 
September, 1955. 

Another form of this so-called "single- 
ended push-pull" style has been used in 
one commercial amplifier (the Stephens 
OTL) and may be used in the future 
because it permits coupling 500-ohm 
speakers directly to the amplifier with- 
out an output transformer. Fig. 10-a 
gives a very simplified diagram of one 
form of this circuit. The two grids re- 
ceive out-of-phase signals. Two power 
supplies are used and balance is achieved 
by returning one grid to an appropriate 



BACKGROUND NOISE 
IN TAPE RECORDING 

By James A. McRoberts 



ELECTRONICS 
IN THE AIR FORCE 

fly Aaron Node// 

Both ore in the 
JUNE 

RADIO-ELECTRONICS 



negative voltage. The output is taken 
off the junction of plate and cathode 
and the impedance can be made low 
enough by paralleling a number of 
tubes to match the low impedance of a 
500- or even a 16-ohm speaker. 

Various methods of driving and of 
supplying the various voltages can be 
used. Fig. 10-b is a simplification of 
the output and driver stages of the 
Stephens amplifier. This configuration 
permits class-B operation but has two 
serious disadvantages: It is extremely 
inefficient even in class-B operation, 
the power output ranging from 1 to 
10% of the input power; there is no 
common load in which distortion can 
be canceled. However, the absence of 
an output transformer permits the use 
of 40 db or more of feedback, which 
compensates for the higher initial dis- 
tortion. It is probable that this circuit 
will appeal" in additional amplifiers in 
the future. 

The driver is a cathode follower 
direct-coupled to the grid of the lower 
output tube. The output tubes are in 
series across the 500-volt supply and 
they feed the load in parallel. Current 
flows from ground through the cathode- 
plate circuit of the lower triode and 
then through the plate and cathode 
circuits of the upper tube. Signal volt- 
age for the upper tube is taken off the 
plate of the lower and grid bias is 
developed by the drop across the cath- 
ode resistor. 

The upper tube sees the lower as a 
cathode resistance shunted by the load 
and the lower sees the upper one as a 
plate load resistor. In each case, the 
load is capacitance-coupled to the 
source. Resistor R between the driver 
plate and the voltage-amplifier cathode 
provides inverse feedback to stabilize 
the amplifier against possible voltage 
drift. 

The internal resistance of the lower 
triode varies as the signal applied to 
its grid. This varies the current through 
the upper triode and develops a signal 
voltage across the load. At the same 
time, the change in current through 
the tubes develops a signal voltage on 
the upper triode grid that is equal to 
and in phase with that applied to the 
lower triode grid. The blocking capac- 
itor prevents dc from flowing through 
the load. end 



62 



RADIO-ELECTRONICS 



www.americanradiohistorv.com 





FOR THE EN 

more t 
qualify 




ELECTRONICS INDUS 



frorrl 



an 65 top- 
models to 
ihcludi 



outstanding 
kit designs/ i 




INDUSTRIAL 
LABORATORIES 



TRAINING 
SCHOOLS 




V-7A VACUUM TUBE VOLTMETER: Easily the world's largest 
selling VTVM. Features peak-to-peak scales— etched metal 
circuit board— 1% precision resistors-full wave rectifier and 
AC input circuit-reads rms and peak- to-- peak AC, DC, and 
ohms. 

0-1 0 LABORATORY TYPE OSCILLOSCOPE: The world's largest 
selling oscilloscope kit, and the most successful oscilloscope 
in history. Designed especially for color and black-and- 
white TV service work. Its 5 megacycle bandwidth and new 
500 Kc sweep generator readily qualify it for laboratory 
applications. Features easy -to -assemble etched metal cir- 
cuit board construction. 



HI-FI 
ENTHUSIASTS 



WA-P2 HIGH FIDELITY PREAMPLIFIER: This is the world's larg- 
est selling hi fi preamplifier kit. Features complete equal- 
ization, 5 separate switch-selected inputs with individual 
pre-set level controls, beautiful modern appearance, high- 
quality components. 

HIGH FIDELITY AMPLIFIERS: Five Heathkit Models to choose 
from at prices ranging from $16.95 to $59.75. Power output 
range from 7 to 25 watts. 

DX-100 TRANSMITTER: A 100 watt phone and CW ham trans- 
mitter, offering the greatest dollar value available in the 
ham radio field today. 



Greatest Dollar Value Through Factory-To-You Selling! 



f 




ONLY ■ lUl^i ■ CAN GIVE YOU ALL 

OF THESE DISTINCTIVE ADVANTAGES! 

. ^ The Most Complete Construction Manuals for Easy Assembly. 

} Originality of Design-Developed Through Pioneering in the Kit Instrument 

Field. 

^ Greatest Dollar Value-Finest Quality with Real Economy. 

jy Direct Contact with Manufacturer-Lower Price, Guaranteed Performance. 

Etched Metal, Prewired Circuit Boards-Save Construction Time, Improve 
Performance. 

High Quality Standard Components for Long-Life Service. 



> 
► 



HEATH COMPANY 



MAY, 1956 



A Subsidiary 
of Daystrom, Inc. 



BENTON HARBOR 20, MICHIGAN 



63 



www.americanradiohistorv.com 




there is no substitute for 

HEATHKIT QUALITY 



YOU GET MORE: All first-run, top quality parts 
—the latest in electronic design —complete and com- 
prehensive step-by-step assembly instructions with 
large pictorial diagrams and assembly drawings. 
Proven performance through the production of 
thousands of kits. 



m 




5 OSCILLOSCOPE KIT 



ETCHED CIRCUIT 

COLOR-TV 



This deluxe quality oscilloscope has proven itself through 
thousands of operating hours in service shops and labora- 
tories. Features the best in components-and the best in 
circuit design. 

Features amplifier response to 5 Mc for color TV work, 
and employs the radically new sweep circuit to provide 
stable operation up to 500,000 cps. In addition, etched metal, 
pre-wired circuit boards cut assembly time almost in half, 
and permit a level of circuit stability never before achieved 
in an oscilloscope of this type. 

Vertical amplifiers flat within +2 db -5 db from 2 cps 
to 5 Mc, down only 1V 2 db.at 3.58 Mc. Vertical sensitivity is 
0.025 volts, (rms) per inch at 1 Kc. 11 tube circuit employs 
a 5UP1 CRT. 

Plastic molded capacitors used for coupling and bypass- 
preformed and cabled wiring harness provided. 

Features built-in peak-to-peak cali- model o-io 
brating source-retrace blanking ampli- $£^50 



0 



LOW CAPACITY 



PROBE KIT 

Scope investigation of circuits encountered in TV re- 
quires the use of special low capacity probe to prevent 
loss of gain, circuit loading, or distortion. This probe 
features a variable capacitor to provide NO 342 
correct instrument impedance matching. C*>C/> 
Also the ratio of attenuation can be con- * w 



trolled. 



Shpg. Wf. I Lb. 



fier-push-pull amplifiers and step-at- 
tenuated input. 



Sh P9 . wt. 21 Lbs. 



© T^Z^&T ETCHED CIRCUIT 

5 OSCILLOSCOPE KIT 

This is a general purpose oscilloscope for the more usual 
applications in the service shop or lab, yet is comparable 
to scopes costing many dollars more. 

Features full size 5" CRT (5BP1), built-in peak-to-peak 
voltage calibration-3 step input attenuator-phasing con- 
trol-push-pull deflection amplifiers-and etched metal pre- 
wired circuit boards. 

Vertical channel flat within ±3 db from 2 cps to 200 Kc, 
with 0.09 V. rms inch, peak-to-peak sen- model om-1 
sitivity at 1 Kc. Sweep circuit from 20 CilACA 
cps to 100,000 cps. A scope you will be 
proud to own and use. Shpg . w,. 2 ? ?b*. 



O 7^£z<^4kT ETCHED CIRCUIT 

SCOPE DEMODULATOR PROBE KIT 

Extend the usefulness of your Oscilloscope by observing 
modulation envelope of R.F. or I.F. carriers found in 
TV and radio receivers. Functions like no. 337-c 
AM detector to pass only modulation of C^Cft 
signal and not signal itself. Applied volt- ▼ 
age limits are 30 V. RMS and 500 V, DC. sh P9 wt 1 ib 



0 



ETCHED CIRCUIT 



3 OSCILLOSCOPE KIT 

This compact little oscilloscope measures only 9%" H. x 
6V2" W. x 11%" D., and weighs only 11 lbs! Easily em- 
ployed for home service calls, for work in the field or is 
just the ticket for use in the ham shack or home work- 
shop. Incorporates many of the features of the Model 
OM-1, but yet is smaller in physical size for portability. 

Employing etched circuit boards, the Model OL-1 fea- 
tures vertical response within ± 3 db from 2 cps to 
200 Kc. Vertical sensitivity is 0.25 V. RMS/inch peak-to- 
peak, and sweep generator operates from 20 cps to 100,000 
cps. Provision for r.f. connection to deflection plates for 
modulation monitoring, and incorpo- model OL-i 



rates many features not expected at 
this price level. 8-tube circuit fe 
a type 3GP1 Cathode Ray Tube. 



this price level. 8-tube circuit features 

$2950 

Shpg. Wt. 14 tbs. 



HEATH COMPANY t^Day^Zlnc. BENTON HARBOR 20, MICHIGAN 



64 



RADIO-ELECTRONICS 



www.americanradiohistorv.com 



fill your - test requirements 

WITH HEATH KITS 



DESIGNED FOR YOU: Heath Company test 
equipment is designed for the maximum in con- 
venience. Besides being functional, Heath kits rep- 
resent the very latest in modern physical appear- 
ance, and incorporate all the latest circuit design 
features for comprehensive test coverage. 





T^ajti&T ETCHED CIRCUIT 

VACUUM 



TUBE 



VOLTMETER KIT 



Besides measuring AC (rms), DC and resistance, the 
modern-design V-7A incorporates peak-to-peak meas- 
urement for FM and television servicing. 

AC (rms) and DC voltage ranges are 1.5, 5, 15, 50, 150, 
500, and 1500. Peak-to-peak AC voltage ranges are 4, 14, 
40 140 400 1400, and 4000. Ohmmeter ranges are XI, X10, 
X100, X1000, X10K, X100K, and XI megohm. Also a db 
scale is provided. A polarity reversing switch provided 
for DC measurements, and zero center operation within 
range of front panel controls. Employs a 200 ua meter 
for indication. Input impedance is 11 megohms. 

Etched metal, pre-wired circuit 
board for fast, easy assembly and re- MODEt V-7A 
liable opi ration is 50% thicker for $QA5Q 
more rugged physical construction. 1% ™ ' • 

precision resistors for utmost accuracy. 



0 



racy. Uses etched circuits for increased 
circuit stability and ease of assembly. 



© 



Shpg. Wt. 7 lbs. 



Q -7tyea#t&Z~ 20,000 ohms/volt 
MULTIMETER KIT 

The MM-1 is a portable instrument for outside servicing, 
for field testing, or for quick portability in the service 
shop. Combines attractive physical appearance with 
functional design. 20,000 ohms/v. DC, and 5000 ohms/v. 
AC. AC and DC voltage ranges are 0-1.5, 5, 50, 150, 500, 
1500 and 5000 volts. Direct current ranges are 0-150 ua., 
15 ma., 150 ma. r 500 ma., and 15 amperes. Resistance ranges 
are XI, X100, X10,000 providing center scale readings of 
15, 1500 and 150,000 ohms. DB ranges cover -10 db to 
4 65 db. 

Features a 4V 2 " 50 ua. meter. Pro- 
vides polarity reversal on DC measure- 
ments. 1% precision resistors used in 
multiplier circuits. Not affected by 
RF fields, sh P9- Wt - 6 Lbs - 



MODEL MM-1 

$2950 



© 



7%>0#fe%?' ETCHED CIRCUIT 

RF PROBE KIT 

The Heathkit RF Probe used in conjunction with any 
11 megohm VTVM will permit RF meas- no. 309-C 
urements up to 250 Mc with ± 10% accu- $^50 

Shpg, Wt. 1 Lb. 

?£6aJ&&<? ETCHED CIRCUIT 

PEAK-TO-PEAK PROBE KIT 

Now read peak-to-peak voltages on the DC scale of 
any 11 megohm VTVM with this new probe, employ- 
ing etched circuit for stability and low no. 338-c 
loss. Readings made directly from $£?50 
VTVM scales, from 5 Kc to 5 Mc. Not # 
required for Heathkit Model V-7AVTVM.Sh P9 . wt,2Lbs. 

7$6z$&<? 30,000 VOLT D C. 

HIGH VOLTAGE PROBE KIT 

For TV service work or similar application for meas- 
urement of high DC voltage. Precision 
multiplier resistor mounted inside plas- ^O^ 336 
tic probe. Multiplication factor of 100 on $4^0 
the ranges of Heathkit 11 megohm 
VTVM. 



Shpg. Wt. 2 Lbs. 



H AN D ITESTE R 



KIT 



The Model M-l measures AC or DC voltage at 0-10, 30, 
300, 1000, and 5000 volts. Measures direct current at 0-10 
ma. and 0>100 ma. Provides ohmmeter ranges of 0-3000 
(30 ohm cerfter scale) and 0-300,000 ohms (3000 ohms 
center scale) . Features a 400 /ja. meter for sensitivity of 
1000 ohms volt. Because of its size, the M-l is a very 
handy portable instrument that will fit in your coat 
pocket, tool box, glove compartment, or desk drawer. 
Makes a fine standby unit in the serv- model M-i 
ice shop when the main instruments $1A50 
are in use, or is ideal for the hobbyist * 
or beginner. An unusual dollar value. Shpg. Wt. 3 Lbs. 



HEATH COMPANY ofDays^troniJnc. 



BENTON HARBOR 20, MICHIGAN 



MAY, I 956 



www.americanradiohistorv.com 



TV ALIGNMENT 

GENERATOR 
KIT > 





HEATH 

COMPANY 

A SUBSIDIARY OF DAYSTROM INC. 



The Model TS-4 features a controllable 
inductor for all-electronic sweep, improved 
oscillator and automatic gain circuitry, 
high RF output, center sweep operation, 
and improved linearity. It sets a new high 
standard for sweep generator operation, 
and is absolutely essential for the up-to- 
date service shop doing FM, black-and- 
white TV, and color TV work. 

Voltage regulation and effective AGC 
action insure flat output over a wide fre- 
quency range. Electronic sweep insures 
complete absence of mechanical vibration. 
Sweep deviation controllable from 0 up to 
40 Mc, depending upon base frequency. Effective two-way blanking. 

Fundamental output from 3.6 Mc to 220 Mc in 4 bands. Crystal marker 
provides markers at 4.5 Mc and multiples thereof. Crystal 
included with kit. Variable marker covers from 19 Mc to 
60 Me on fundamentals, and up to 180 Mc on harmonics. 
Provision for external marker. 




MODEL TS-4 

$4950 



0 



e 



Shpg. Wi. 16 Lbs. 

TfyeafitAtf LINEARITY PATTERN 

GENERATOR KIT 

The new-design Model LP-1 produces vertical or horizontal bar pat- 
terns, a cross-hatch pattern, or white dots on the screen of the TV 
set under test. No internal connections required. Special clip is 
attached to the TV antenna terminals. Instant selection of the pattern 
desired for adjustment of vertical and horizontal linearity, picture size, 
aspect ratio, and focus. Dot pattern presentation is a must for color 
convergence adjustments on color TV sets. model lp-i 

Extended operating range covers all television chan- (aaca 
nels from 2 to 13. Produces 6 to 12 vertical bars or *^^ aw 
4 to 7 horizontal bars. $h P3 .wt. 7*bs. 

7^^^T LABORATORY 

GENERATOR KIT 

The Heathkit Model LG-1 Laboratory Generator is a high-accuracy 
signal source for applications where metered performance is essential 
It covers from 100 Kc to 30 Mc on fundamentals in 5 bands. Modu- 
lation is at 400 cycles, and modulation is variable from 0-50%. RF 
output from 100,000 uv. to 1 uv. 200 pa. meter reads the RF output 
in microvolts, or percentage of modulation. Fixed step and variable 
output attenuation provided. model lg-i 

Features voltage regulation, and double copper plated (a A ca 
shielding for stability. Provision for external modula- 'v™ W 
tion. Coaxial output cable (50 ohms). Shpg.wt. J6*b s . 



CATHODE RAY 



TUBE CHECKER KIT 

This new-design instrument holds the key to rapid and complete 
picture tube testing, either in the set, on the work-bench, or in the 
carton. Tests for shorts, leakage, and emission. Features Shadow- 
graph test (a spot of light on the screen) to indicate whether the tube 
is capable of functioning. 

The Model CC-1 tests all electromagnetic deflection picture tubes 
normally encountered in television servicing. Supplies all. operating 
voltages to the tube under test, and indicates the condition of the tube 
on a large "GOOD-BAD" scale. Features spring loaded model cc-i 
test switches for operator protection. SO^I^O 

The CC-1 is housed in an attractive portable case # 
and is light in weight - ideal for outside service calls. Shpg.wt. io Lbs. 



DIRECT READING 



CAPACITY METER KIT 

Not only is this instrument popular in the service shop, but it has 
found extensive application in industrial situations. Ideal for quality 
control work, production line checking, or for matching pairs. 

Features direct reading linear scales from 100 mmf to .1 mfd full 
scale. Necessary only to connect a capacitor of unknown value to 
the insulated binding posts, select the correct range, model cm-i 
and read the meter. The CM-1 is not susceptible to C*%A50 
hand capacity, and has a residual capacity of less than ^ 

1 mmf - Shpg.Wt. 7 Lbs, 



BENTON HARBOR 2 0, MICHIGAN 



66 



RADIO- ELECTRONICS 



www.americanradiohistorv.com 




This is one of the biggest signal generator bar- 
gains available today. The tried and proven 
Model SG-8 offers all of the outstanding fea- 
tures required for a basic service instrument. 
High quality components and outstanding per- 
formance. 

The SG-8 covers 160 Kc to 110 Mc on funda- 
mentals in 5 bands, and calibrated harmonics 
extend its usefulness up to 220 Mc. The output 
signal is modulated at 400 cps, and the RF 
output is in excess of 100,000 uv. Output con- 
trolled by both a continuously variable and a 
fixed step attenuator. Also, audio output may 
be obtained for amplifier testing. Don't let the 
low price deceive you. This is a professional type service instrument to fulfill 
the signal source requirements in the service lab. 



MODEL SG-8 

Shpg. Wf. 8 Lbs. 



$1950 



double as a battery charger. Definitely required for auto- 
mobile radio service work. 



© -//ea#£&Z~ DECADE RESISTANCE KIT 



Twenty 1% precision resistors provide resistance from 1 to 
99.999 ohms in 1 ohm steps. Indispensible around service 
shop laboratory, ham shack, or home workshop. Well worth 
the extremely low Heathkit price. 



MODEL DR-l 

$1950 

Shpg. V/t. A Lbs. 




J 



O IMPEDANCE BRIDGE KIT 

The IB-2 features built-in adjustable phase shift oscillator and amplifier, 
and has panel provisions for external generator. Measures resistance, capaci- 
tance, inductance, dissipation factors of condensers, and storage factor of 
inductance. 

D, Q, and DQ functions combined in one control. Vt% resistors and l /z% 
silver-mica capacitors especially selected for this instru- model ib-2 
ment. A 100-0-100 microammeter provides null indications. SCO50 
Two-section CRL dial provides 10 separate "units" with an # 
accuracy of .5%. Fractions of units read on variable control. Sb P9 . v/t. 12 Lbs. 

© 7%a#6&T "Q" METER KIT 

The Heathkit Model QM-1 will measure the Q of inductances and the RF 
resistance and distributed capacity of coils. Employs a 4V 2 " 50 microampere 
meter for direct indication. Will test at frequencies of 150 Kc to 18 Mc in 4 
ranges. Measures capacity from 40 mmf to 450 mmf within ± 3 mmf. Indis- 
pensible for coil winding and determining unknown condenser values. A 
worthwhile addition to your laboratory at an outstandingly MO del OM-l 
low price. Useful for checking wave traps, chokes, peaking SAASO 
coils, etc. Laboratory facilities are now available to the ^"§"§ B 
service shop and home lab. Sb P3- vvt. u Lbs. 

Q 7^W^T 6-12 VOLT 

BATTERY ELIMINATOR KIT 

This modern battery eliminator will supply 6 or 12 volt output for ordinary 
automobile radios as well as 12 volts for the new models in the latest model 
cars. Output voltage is variable from 0-8 volts DC, or 0-16 volts DC. Will 
deliver up to 15 amperes at 6 volts, or up to 7 amperes at 12 volts. Two 
10,000 microfarad filter capacitors insure smooth DC output. model be-4 
Two panel meters monitor output voltage and current. Will $3|50 

Shpg. Wf. 17 Lbs. 



KIT 




I 
I 
I 
I 
I 
I 
I 
I 
I 



Hb—& * w mm 



© 7^S^r VIBRATOR TESTER KIT 

Tests vibrators for proper starting and indicates the quality of the output 
on a large "GOOD-BAD" scale. Checks both interrupter model vt-i 
and self -rectifier types in 5 different sockets. Operates from $1 A50 
any battery eliminator delivering variable voltage from 4 # 
to 6 volts DC at 4 amps. Ideal companion to the Model BE-4. Sh Pg . wi. 6 Lbs. 

0 TYeaM^r DECADE CONDENSER KIT 

Provides capacity values from 100 mmf to 0.111 mfd in steps of 100 mmf. 

± 1% precision silver-mica condensers used. High quality model dc-i 

ceramic switches for reduced leakage. Polished birch cab- $14%50 
inet. Extremely valuable in all electronic activity. # 

Shpg. Wf. 3 Lbs. 



BENTON HARBOR 20, MICHIGAN <^ 

MAY, 1956 




COMPANY 

A SUBSIDIARY Of DAY&TROM INC. 



www.americanradiohistorv.com 




TUBE 
CHECKER 

KIT 



HEATH 

COMPANY 

A SUBSIDIARY OF DAYS T ROM INC 



0 




OThe Heathkit Model TC-2 is an emission type tube tester that repre- 
sents a tremendous saving over the price of a comparable unit from any 
other source. At only $29.50, you can have a tube tester of your own, even 
if you are an experimenter, or only do part time service work. Extremelv 
popular with radio servicemen, it uses a 4M>" meter with 3-color meter face for 
simple "GOOD-BAD" indications that the customer can understand. Will test- 
all tubes commonly encountered in radio and TV service work. 

Ten 3-position lever switches for "open" or "short" tests on each tube ele- 
ment. Neon bulb indicates filament continuity or short between tube elements. 
Line adjust control provided. The roll chart is illuminated. 

Sockets provided for 4, 5, 6, and 7-pin, octal, and loctal 
tubes, 7 and 9 pin miniature tubes, and the 5 pin Hytron 
tubes. Blank space provided for future socket addition. Tests 
tubes for opens, and shorts, and for quality on the basis of 
total emission. 14 different filament voltage values provided. 



MODEL TC-2 

$2950 

Shpg. Wt. 12 Lbs. 



7%ad£&? PORTABLE TUBE CHECKER KIT 



The Model TC-2P is identical to the Model TC-2 except that it is housed 
in a rugged carrying case. This strikingly attractive and practical two-tone case 
is finished in proxylin impregnated fabric. The cover is de- model TC-2P 
tachable, and the hardware is brass plated. This case imparts 
a real professional appearance to the instrument. Ideal for 
home service calls, or any portable application. 



$3450 

Shpg. Wt. 15 Lbs. 



TV PICTURE TUBE TEST ADAPTER 



The Heathkit TV picture tube test adapter is designed for use 
with the Model TC-2 Tube Checker. Test picture tubes for 
emission, shorts, and thereby determine tube quality. Consists 
of 12-pin TV tube socket, 4 ft. cable, octal connector, and 
necessary technical data. (Not a kit.) 



MODEL 355 

$450 

Shpg. Wt. f # lb. 



CONDENSER CHECKER KIT 

Use this Condenser Checker to quickly and accurately measure those un- 
known condenser and resistor values. All readings taken directly from the 
calibrated panel scales without any involved calculation. Capacity measure- 
ments in four ranges from .00001 to 1000 mfds. Checks paper, mica, ceramic and 
electrolytic condensers. A power factor control is available for accurate indi- 
cation of electrolytic condenser efficiency. Leakage test switch-selection of five 
polarizing voltages, 25 volts to 450 volts DC to indicate condenser operating 
quality under actual load conditions. Spring-return test switch automatically 
discharges condenser under test and eliminates shock hazard to the operator. 

Resistance measurements can be made in the range from 100 ohms to 5 meg- 
ohms. Here again, all values are read directly on the calibrated scales. Increased 
sensitivity coupled with an electron beam null indicator in- 
creases overall instrument usefulness. model C-3 
For safety of operation, the circuit is entirely transformer C«ACA 
operated. An outstanding low kit price for this surprisingly 
accurate instrument. 



Shpg. Wt. 7 Lbs. 



VISUAL-AURAL 



68 



SIGNAL TRACER KIT 

This signal tracer is extremely valuable in servicing AM, FM, and TV receivers, 
especially when it comes to isolating trouble to a particular stage of the circuit 
under test. 

This visual-aural tracer features a high gain RF input channel to permit 
signal tracing from the receiver antenna input clear through all RF, IF, de- 
tector, and audio stages to the speaker. Separate low-gain channel provided 
for audio circuit exploration. Both visual and aural indication by means of a 
speaker or headphone, and electron beam "eye" tube as a level indicator. Also 
incorporates a noise locater circuit for DC noise checks, and a built-in cali- 
brated wattmeter (30-500 watts). Panel terminals provided 
for "patching" output transformer or speaker into external model t-3 
circuit for test purposes. Designed especially for the radio <«%*)Cn 
and TV serviceman. Cabinet size: 9Vfe" wide x $W high x 5" '23 
deep. A real test equipment bargain. Shpg w , 9 * bs 

[J BENTON HARBOR 20, MICHIGAN 

RADIO-ELECTRONICS 



www.americanradiohistorv.com 




Shpg. Wf. 13 Lbs. 



MODEl HD-1 

$4950 



Used with a sine wave generator, the Model 
HD-1 will check the harmonic distortion out- 
put of audio amplifiers under a variety of 
conditions. Reads distortion directly on the 
meter as a percentage of the input signal. 
Operates between 20 and 20,000 cps. High 
impedance VTVM circuit for initial reference 
settings and final distortion readings. Ranges 
are 0-1, 3, 10, and 30 volts full scale. 1% pre- 
cision resistors. Distortion scales are 0-1, 3, 
10, 30 and 100% full scale. Requires only .3 
volt input for distortion test. 



o 



T^^T AUDIO ANALYZER KIT 

This instrument consists of an audio wattmeter, an AC VTVM, and a 
complete IM analyzer, all in one compact unit. 

Use the VTVM to measure noise, frequency response, output gain, power 
supply ripple, etc. Use the wattmeter for measurement of power output. 
Internal loads provided for 4, 8, 16, or 600 ohms. VTVM also calibrated for 
DBM units. High or low impedance IM measurements made model aa-1 
with built-in 6KC and 60 cps generators. VTVM ranges are CJCO50 
.01, to 300 volts in 10 steps. Wattmeter ranges are .15 mw. # 
to 150 w. in 7 steps. IM scales are 1% to 100% in 5 steps. Shpg.wt. 13 Lbs. 

© -//eatftM AUDIO GENERATOR KIT 

This new Heathkit Model features step- tuning from 10 cps to 100 Kc with 
three rotary switches that provide two significant figures and multiplier. 
Less than .1% distortion. Frequency accurate to within ± 5%. 

Output monitored on a large 4V 2 " meter that reads voltage or db. Both 
variable and step-type attenuation provided. Meter reads zero-to-maximum 
at each attenuator position. Output ranges (and therefore M0DEL AG 9 
meter ranges) are 0-.003, .01, .03, .1, .3, 1, 3, 10 volts. Step- 
tuning provides rapid positive selection of the desired fre- 9 04 # 
quency, and allows accurate return to any given frequency. Shpg. Wt. 8 Lbs, 

Q y/eaM^ AUDIO OSCILLATOR KIT 

(SINE WAVE — SQUARE WAVE) 

The Model AO-1 features sine wave or square wave coverage from 20-20,000 
cps in 3 ranges. It is an instrument specifically designed to completely 
fulfill the needs of the serviceman and high fidelity enthusiast. Offers high 
level output across the entire frequency range, low distortion and low 
impedance output. Features a thermistor in the second amplifier stage to 
maintain essentially flat output through the entire fre- 
quency range. Produces an excellent sine wave for audio 
testing, or will produce good, clean, square waves with a 
rise time of only 2 microseconds. 

y/ea^cC RESISTANCE 
SUBSTITUTION BOX KIT. 

Provides switch selection of 36 RTMA 1 watt standard 1% 
resistors ranging from 15 ohms to 10 megohms. Numerous 
applications in radio and TV work, and essential in the 
developmental laboratory. 



o 



MODEL AO-1 

$2450 

Shpg. Wt. 10 Lbs 



MODEL RS-1 

$550 

Sbpg. Wt. 2 Lbs. 



Q i4ea#i&Z~ ac vacuum tube 

VOLTMETER KIT... 

The Heathkit AC VTVM features high impedance, wide frequency range, 
very high sensitivity, and extremely wide voltage range. Will accurately 
measure a voltage as small as 1 mv. at high impedance. Excellent for 
sensitive AC measurements required by laboratories, audio enthusiasts and 
experimenters. Frequency response is substantially fiat from m0 del av-2 
10 cps to 50 Kc. Ranges are .01, .03, .1, .3, 1, 3, 10, 30, 100, S 0«50 
and 300 v. RMS. Total db range -52 to + 52 db. Input 
impedance 1 megohm at 1 Kc. Shpg. wt. 5 tbs. 

O ^4a^U^ CONDENSER 

SUBSTITUTION BOX KIT... 




Very popular companion to Heathkit RS-1. Individual selec- 
tion of 18 RTMA standard condenser values from .0001 mfd 
to .22 mfd. Includes 18" flexible leads with alligator clips. 



MODEL CS-1 

$550 

Shpg.Wt. 2 Lbs. 



BENTON HARBOR 2 0, MICHIGAN <| 



HEATH 

COMPANY 

A SUBSIDIARY OF DAYS7ROM INC. 



MAY. 1956 



69 



www.americanradiohistorv.com 



HEATHKIT HAM GEAR 




for high quality at moderate cost 




DOLLAR VALUE: You get more for your 
Heat hh it dollar because your labor is used to 
build the kit instead of paying for someone else's. 
Also, the middleman's margin of profit is elim- 
inated when you deal directly with the manu- 
faciu rer. 




© T^S^T DX-lOO PHONE & 
CW TRANSMITTER KIT 

The reception given this amateur transmitter has been 
tremendous. Reports from radio amateurs using the DX-100 
are enthusiastic in praising its performance and the high 
quality of the components used in its assembly. Actual 
"on the air" results reflect the careful design that went 
into its development. 

The DX-100 features a built-in VFO, modulator, and 
power supplies, and is completely bandswitching for phone 
or CW operation on 160, 80, 40, 20, 15, 11, and 10 meters. All 
parts necessary for construction are supplied in the kit, 
including tubes, cabinet, and detailed step-by-step instruc- 
tions. Easy to build, and a genuine pleasure to operate. 

Employs push-pull 1625's modulating parallel 6146's for 
RF output in excess of 100 watts on phone and 120 watts 
on CW. May be excited from the built-in VFO or from 
crystals (crystals not included with kit). Features five- 
point TVI suppression: (1) pi network interstage coupling 
to reduce harmonic transfer to the final stage; (2) pi net- 
work output coupling; (3) extensive shielding; (4) all in- 
coming and outgoing circuits filtered; (5) inter-locking 
cabinet seams to eliminate radiation except through the 
coaxial output connector. Pi network output coupling will 
match 50 to 600 ohm non-reactive load. Illuminated VFO 
dial and meter face. Remote control socket provided. 

The chassis is made of extra-strong #16 gauge copper- 
plated steel. It employs potted transformers, ceramic switch 
and variable capacitor insulation, solid silver loading switch 
terminals, and high-grade well-rated components through- 
out. Features a pre-formed wiring harness, and all coils 
are prc-wound. 

High-gain speech amplifier for dynamic or crystal micro- 
phones, and restricted speech range for increased intelli- 
gence. Plenty of audio power reserve. 

Measures 20%" W. x 13%" H. x 16" D. MODEL M-ioo 

Schematic diagram and complete 5|JJ9^ 
technical specifications on request. shpg. wt. i20*Lbs. 

Shipped Motor Freight Unless Otherwise Specified 
$50.00 Deposit Required on C.O.D. Orders 



0 



VFO KIT 



The Model VF-1 covers 160-80-40-20-15-11 and 10 meters 
with three basic oscillator frequencies. Better than 10-volt 
average RF output on fundamentals. Features illuminated 
and pre-calibrated dial scale. Cable and plug provided to 
fit crystal socket of any modern transmitter. 

Enjoy the convenience and flexibility of VFO operation 
at no more than the price of crystals. May be powered 
from plug on the Heathkit Model AT-1 
transmitter, or supplied with power from 
most transmitters. Measures: 7" H x 
W W. x 7" D. 



MODEL VF-1 

$1950 

Shpg. Wt. 7 Lbs. 



© T^Ojtf&f CW AMATEUR 

TRANSMITTER KIT 

The Model AT-1 is an ideal novice transmitter, and may be 
used to excite a higher power rig later on. 

This CW transmitter is complete with its own power 
supply, and covers 80, 40, 20, 15, 11, and 10 meters. Features 
single-knob bandswitching, and panel meter indicates grid 
or plate current for the final amplifier. Designed for crystal 
operation or external VFO. Crystal not included in kit 
Incorporates such features as key click filter, line filter, 
copper-plated chassis, pre-wound coils, 52 ohm coaxial out- 
put, and high quality components 
throughout. Instruction book simplifies 
assembly. Employs a 6AG7 oscillator, 
6L6 final amplifier. Operates up to 35 $29^ 
watts plate power input. Shpg . w , I5 # lfaj 

ANTENNA COUPLER KIT 

The Model AC-1 will properly match your low power trans- 
milter to an end-fed long wire antenna. Also attenuates 
signals above 36 Mc, reducing TVI. 52 ohm coax, input- 
power up to 75 watts-10 through 80 meters-tapped induc- 
tor and variable condenser-neon RF in- model 
dicator-copper plated chassis and high cl -^ 
quality components. Ideal for use with 5|^50 
Heathkit AT-1 Transmitter. shpg. wt. fibs 



HEATH COMPANY benton harbor 20, Michigan 



70 



RADIO-ELECTRONICS 



www.americanradiohistorv.com 



"AMATEUR-ENGINEERED" 



Equipment For The Ham 



MODERN DESIGN: You can be sure of 
getting all the latest and most desirable 
design features when you buy Heathkits. 
Advanced-design is a minimum standard 
for new Heath kit models. 




MODEL AR-3 




7^&^&T COMMUNICATIONS-TYPE 

ALL BAND RECEIVER KIT 

The new Model AR-3 features improved IF and RF 
performance, along with better image rejection on all 
bands. Completely new chassis layout for easier as- 
sembly, even for the beginner 

Covers 550 Kc to 30 Mc in four bands. Provides sharp 
tuning and good sensitivity over the entire range. 
Features a transformer-type power supply— electrical 
bandspread— separate RF and AF gain controls— antenna 
trimmer— noise limiter— AGC-BFO— headphone jacks— 
5Vfe" PM speaker and illuminated tun- 
ing dial. 



MODEL AR-3 



aluminum panel as shown. Part No. 91- 
15, shipping weight 5 lbs. $4.50. 



Shpg Wt. 12 Lbs. 
(Less Cabinet) 



0 y^a^^ 

"Q" MULTIPLIER KIT 

Here is the Heathkit Q Multiplier you hams have been 
asking for. A tremendous help on the phone and CW 
bands when the QRM is heavy. Provides an effective 
Q of approximately 4,000 for extremely sharp "peak" 
or "null." Use it to "peak" the desired signal or to 
"null" an undesired signal, or heterodyne. Tunes to any 
signal within the IF band-pass of your receiver. Also 
provides "broad peak" for conditions where extreme 
selectivity is not required. 

Operates with any receiver having an IF frequency 
between 450 and 460 Kc. Will not function with AC-DC 
type receivers. Requires 6.3 volts AC at 300 ma. and 150 
to 250 VDC at 2 ma. Derives operating power from 
your receiver. Uses a 12AX7 tube, and special High-Q 
shielded coils. Simple to connect with 
the cable and plugs supplied. Measures 
only 4-11 16"H.x7%"W.x4ft"D. A really 
valuable addition to the receiving 
equipment in your ham shack. Shpg. wt. 3 lb$. 



MODEL QF-1 

$995 



© y/ea&l&C VARIABLE VOLTAGE 

REGULATED POWER SUPPY KIT 

Provides well filtered DC output, variable from zero to 500 
volts at no load and regulated for stability. Will supply up to 
10 ma. at 450 VDC, and up to 130 ma. at 200 VDC. Voltage or 
current monitored on front panel meter. Also provides 6.3 
VAC at 4A. for filament. Filament voltage isolated from B-f-, 
and both isolated from ground. Invaluable around the ham 
shack for supplying operating potentials to M0DEL PS 3 
experimental circuits. Use in all types of re- " 
search and development laboratories as a $35 
temporary power supply, and to determine de- • 
sign requirements for ultimate power supply. Shpg. wt. 17 /b*. 

^} 7^&^&T ANTENNA 

IMPEDANCE METER KIT 

Use in conjunction with a signal source for measuring antenna 
impedance, line matching, adjustment of beam and mobile 
antennas, etc. Will double as a phone monitor 
or relative field strength indicator. 100 pa. 
meter employed. Covers the range from 0-600 
ohms. An instrument of many uses for the 
amateur. 



MODEL AM-l 

*14 5 . 0 

Shpg. Wt. 2 lb. 



© tYcoMU GRID DIP METER KIT 

This is an extremely valuable tool for accomplishing literally 
hundreds of jobs on all types of equipment. Covering from 
2 Mc to 250 Mc, the GD-1B is compact and can be operated 
with one hand. Uses a 500 ^ia. meter for indi- M0DEL GD 1B 
cation, with a sensitivity control and head- * 
phone jack. Includes prewound coils and rack. $10->0 
Indispensable instrument for hams, engineers, • 
or servicemen. Shpg. wt. 4 lbs. 



HEATH COMPANY ttlt^Zinc. benton harbor 20, Michigan 



MAY, 1956 



71 



www.americanradiohistorv.com 



PROVIDE THE 
"CONSTRUCTIVE" 
APPROACH TO 

HIGH-FIDELITY 




EASY TO BUILD: The assembly instruc- 
tions supplied with Heathkits are so 
complete and detailed that anyone can 
assemble the hits without difficulty. Plenty 
of pictorial diagrams and step-by-step in- 
structions. Information on resistor color 
codes, soldering, use of tools, etc. Build-it- 
yourself with confidence! 




T^O^^T ADVANCED-DESIGN 

AMPLIFIER KIT 



HIGH 

FIDELITY 



The 25 Watt Model W-5 is one of the most outstanding high fidelity amplifiers 
available today— at any price. Incorporates the very latest design features to 
achieve true "presence" for the super-critical listener. 

Features a new-design Peerless output transformer, and KT66 output tubes 
handle power peaks up to 42 watts. The unique "tweeter-saver" suppresses high 
frequency oscillation. A new type balancing circuit results in closer "dynamic" 
balance between output tubes. Features improved phase shift characteristics 
and frequency response, with reduced IM and harmonic distortion. Color styling 
harmonizes with the Heathkit WA-P2 Preamplifier and the FM-3 Tuner. 

Frequency response— within ± 1 db from 5 cps to 160 Kc at 1 watt. Harmonic 
distortion only 1% at 25 watts, 20-20,000 cps. IM distortion only 1% at 20 watts, 
using 60 and 3,000 cps. Output impedance 4, 8, or 16 ohms. Hum and noise— 99 db 
below rated output. Uses two 12AU7's, two KT66's and a 5R4GY. 
KIT COMBINATIONS: 

W-5M Amplifier Kit: Consists of main amplifier and 
power supply, all on one chassis. Complete with all neces- 
sary parts, tubes, and comprehensive manual. Shpg. Wt. 
31 lbs. Express only. 

W-5 Combination Amplifier Kit: Consists of W-5M 
Amplifier Kit listed above plus Heathkit Model WA-P2 
Preamplifier Kit. Complete with all necessary parts, 
tubes, and construction manuals. Shpg. Wt. 38 lbs. Ex- 
press only. 



75 
50 



Q 7^a^t^ DUAL-CHASSIS WILLIAMSON TYPE 

AMPLIFIER KIT 



HIGH 

FIDELITY 



This is a very popular high fidelity amplifier kit that features dual-chassis type 
construction. The resulting physical dimensions offer an additional margin of 
flexibility in installation. It features the famous Acrosound TO-300 "ultra-linear" 
output transformer, and has a frequency response within ± 1 db from 6 cps to 
150 Kc at 1 watt. Harmonic distortion only 1% at 21 watts. IM distortion at 20 
watts only 1.3% at 60 and 3,000 cps. Rated power output is 20 watts. Output im- 
pedance 4, 8, or 16 ohms. Hum and noise-88 db below 20 watts. Uses two 6SN7's, 
two 5881's, and a 5V4G. 

KIT COMBINATIONS: 

W-3M: Consists of main amplifier and power supply for 
separate chassis construction. Includes all tubes and com- 
ponents necessary for assembly. Shpg. Wt. 29 lbs., Express 
only. 

W-3: Consists of W-3M Kit listed above plus Heathkit 
Model WA-P2 Preamplifier described on opposite page. 
Shpg. Wt. 37 lbs., Express only. 



75 
50 



© 



7%a36&T SINGLE-CHASSIS WILLIAMSON TYPE 

AMPLIFIER KIT 



HIGH 

FIDELITY 



This is the lowest priced Williamson type amplifier ever offered in kit form, and 
yet it retains all the usual features of the Williamson type circuit. Main amplifier 
and power supply combined on one chassis, and uses a new-design Chicago 
output transformer. Frequency response— within ± 1 db from 10 cps to 100 Kc 
at 1 watt. Harmonic distortion only 1.5% at 20 watts. IM distortion at rated out- 
put, 2.7% at 60 and 3,000 cps. Rated power output is 20 watts. Output impedance 
4, 8, or 16 ohms. Hum and noise— 95 db below 20 watts. Uses two 6SN7's, two 
5881's, and one 5V4G. 

Instructions are so complete that the kit may be assembled successfully even 
by a beginner in electronics. 

KIT COMBINATIONS: 

W-4AM: Consists of main amplifier and power supply for 
single chassis construction. Includes all tubes and com- 
ponents necessary for assembly. Shpg. Wt. 28 lbs. Express 
only. 

W-4A: Consists of W-4AM Kit listed above plus Heathkit 
Model WA-P2 Preamplifier described on opposite page. 
Shpg. Wt. 35 lbs. Express only. 



75 
50 



> BENTON HARBOR 20, MICHIGAN 



RADIO-ELECTRONICS 



COMPANY 

A SU&StDIARY OF DAYSTROM INC. 



www.americanradiohistorv.com 




ATTRACTIVELY STYLED: Heathkit 
high fidelity instruments are not only func- 
tional, but are most attractive in physical 
design. Such units as the preamplifier and 
the W-5 main amplifier are designed for 
beauty as well as performance. They blend 
with any room decor and are the hind of in- 
struments you will be proud to own. 



T^OdfaiT HIGH FIDELITY 

PREAMPLIFIER KIT 

This outstanding preamplifier is designed specifically for use with the 
Heathkit Williamson type amplifiers. It completely fulfills the requirements 
for remote control, compensation and preamplification, and exceeds even 
the most rigorous specifications for high fidelity performance. 

Features five separate switch -selected input channels (2 low level and 
3 high level), each with its own input control. Full record equalization 
with four-position turnover control and four-position rolloff control. 

Output jack for tape recorder — separate bass control with 18 db boost 
and 12 db cut at 50 cps. - treble control offering 15 db boost and 20 db cut 
at 15,000 cps — special hum control to insure minimum hum level — and 
many other desirable features. Overall frequency response (with controls 
set to "flat" position) is within 1 db from 25 cps to 30,000 cps. Will do justice 
to the finest available program sources. Beautiful satin-gold fiinish. 

Power requirements from the Heathkit Williamson type ^tM^y r * 
high fidelity amplifier - 6.3 VAC at 1 amp., and 300 VDC at $| V. 
10 Ma. Uses two 12AX7*s and one 12AU7. Shpg. wt. 7 lb*. 

-WATT HIGH FIDELITY 

AMPLIFIER KIT 

This Heathkit Model offers you the least expensive route to high fidelity 
performance. Frequency response is ± 1 db from 20-20,000 cps. Features 
full 20 watt output using push-pull 6L6's, and incorporates separate bass 
and treble tone controls. Preamplifier and main amplifier are built on the 
same chassis. Four switch -selected compensated inputs and separate bass 
and treble tone controls provide all necessary functions at minimum in- 
vestment. Features miniature tube types for low hum and noise. 

Uses 12AX7, two 12AU7*s, two 6L6G's and a 5V4G. A most interesting 
"build-it-yourself" project, and an excellent hi-fi amplifier MODEL A 9B 
for home use. Well suited, also, for public address applica- 
tions because of its high power output and high quality ▼ 05 . 
audio reproduction. Another Heathkit "best-buy" for you! Shpg. Wf. 23 lbs. 



e 



7%0$&<f 7 - W A T T 

AMPLIFIER KIT 



The redesigned Model A-7D features a new type output transformer for 
tapped screen operation, and provides improved sensitivity, reduced distor- 
tion, and increased power output. 

The full 7-watt output of the Model A-7D is more than adequate for nor- 
mal home installations. Frequency characteristics are ± lVfe db from 20 to 
20,000 cps. Potted output and power transformers employed. Push-pull 
output - detailed construction manual - top quality parts M0DEL A 7D 
- high quality audio without great expense. Output trans- „ - 0 - 
former tapped at 4, 8, and 16 ohms. Bass and treble tone ?lO . 
controls provided on the front chassis apron. sfcpg. Wf. 70 lbs. 

Model A-7E: Provides a preamplifier stage with two switch-selected 
inputs and RIAA compensation for variable reluctance or low level 
cartridges. Preamplifier built on same chassis as main amplifier. Model 
A-7E. Shipping weight 10 lbs. S18.50. 



BENTON HARBOR 20, M I C H I G A 

MAY, 1956 



THE VERY BEST 
IN AUDIO WITH 
BUILD-IT-YOURSELF" 

HEATHKITS 




www.americanradiohistorv.com 



FM TUNER 



EATHKIT HIGH-FIDELITY 

KIT 





MODEL FM-3 

$ 24 s .° 



Shpg. Wt 
7 lb*. 

( with cabinet ) 



The new Heathkit Model FM-3 features tremendous circuit 
improvements and brand new physical design. Sensitivity is 
better than 10 uv. for 20 db of quieting, and it employs a 
completely modern tube line-up for high gain and stable 
operation. Incorporates its own power supply, and has pro- 
vision for low-level or high-level output at low impedance. 

The attractive Model FM-3 matches the WA-P2 Pre- 
amplifier in color, styling, and physical size. 

Incorporates automatic gain control, a highly stabilized 
oscillator, and illuminated tuning dial. Educational treat- 
ment of construction manual simplifies assembly for the 
newcomer to electronics. IF and ratio transformers are pre- 
aligned, and the front-end tuning unit is pre-assembled and 
aligned. Uses 6BQ7A as a cascode type RF stage, 6U8 oscil- 
lator-mixer, two 6CB6's as IF amplifiers, a 6AL5 ratio de- 
tector, a 6C4 audio amplifier, and 6X4 rectifier. 



Brand New, Modern FM Circuit Using Latest Type 
Miniature Tubes. 

Low-Noise Cascode RF Stage-Two IF's-Ratio Detector- 
Stage of Audio. 

Extremely Good Sensitivity and Band-Pass for Outstand- 
ing Performance. 

Strikingly Attractive Satin-Gold Finish to Match Heath- 
kit Model WA-P2 Preamplifier. 

Compact Physical Dimensions for Most Pleasing Appear- 
ance and Increased Circuit Efficiency. 



HEATHKIT B R O A D C A ST- B A N D 

Build your own radio receiver with con- 
fidence, even if you are a beginner. Com- 
plete instructions supplied. 

Features transformer- type power sup- 
ply, high-gain miniature tubes, built-in 
antenna, 5V£" speaker, and planetary 
tuning from 550 Kc to 1500 Kc. Adapt- 
able for use as AM Tuner and phono 
amplifier. Educational treatment of the 
construction manual helps the beginner 
learn about radio circuits and parts as 
he builds. 

CABINET: Fabric covered plywood cabi- 
net with aluminum panel as shown. Part 
91-9, Shpg. Wt. 5 lbs., $4.50. 



RECEIVER KIT 




MODEL BR-2 



$1750 



Shpg. Wf. 



Cabinet 
10 lbs. 



Are you on our mailing list? If not— how about sending us your name? 




SHIP VIA 

□ Parcel Post 

□ Express 

□ Freight 

□ Best Way 



QUANTITY 


ITEM 


MODEL NO. 


PRICE 



































































































NOTE: ALL PRICES SUBJECT TO CHANGE WITHOUT NOTICE. 

Enclosed find ( ) check ( ) money order for Please ship C.O.D. ( ) postage enclosed for pounds. 

On Express orders do not include transportation charges — they will be collected by the express agency at time of delivery. 

ON PARCEL POST ORDERS include postage for weight shown. ORDERS FROM CANADA and APO's must include full remittance. 



HEATH COMPANY 



A Subsidiary 
of Daystrom, Inc. 



BENTON HARBOR 20, MICHIGAN 



74 



RADIO-ELECTRONICS 



www.americanradiohistorv.com 



AUDIO— HIGH FIDELITY 




Part I — Correcting poor frequency 
response and insufficient erase 



By HERMAN BURSTEIN 



TAPE recorder troubles may be 
divided into two kinds: mechan- 
ical, involving the transport mech- 
anism; electronic, involving the 
audio preamplifiers, equalization cir- 
cuits, bias oscillator and record level 
indicator. Principally the electronic 
problems are discussed in this article. 

Except for minor repairs and adjust- 
ments, such as replacing a belt or 
aligning a head, it is too often a losing 
proposition for the service technician 
to repair an unfamiliar device that 
has developed serious mechanical diffi- 
culty. As with record changers, serv- 
icing the transport mechanism is fre- 
quently a matter for the factory or 
specialist, found in large cities, pri- 
marily engaged in the repair of phono- 
graphs and tape recorders. 

Because of the large number of re- 
corders on the market and the great 
variation in their mechanical design, 
servicing these units requires a stock 
of many special parts and extensive 
know-how. Large volume enables the 
specialist to meet these requirements. 
However, with minor exceptions, the 
electronic portion of tape recorders can 
be serviced with standard components 
— tubes, resistors, capacitors — that the 
service technician normally has on hand. 
Familiarity with the principles of 



tape recording should enable the tech- 
nician already adept at radio, TV and 
high-fidelity troubleshooting to cope 
with electronic troubles in tape re- 
corders. These may be classed as: poor 
frequency response, insufficient erase, 
weak or no sound, distortion, hum and 
noise. 

This article is concerned with restor- 
ing tape-recorder performance to orig- 
inal quality rather than with improving 
upon the manufacturer's product. How- 
ever, for some problems, such as hum 
and noise, there are measures which 
can be tried to improve on original 
performance — if the customer desires 
and at reasonable cost. 

Frequency response 

The setup in Fig. 1 can be used to 
check frequency response. Note that 
response is measured at the output of 

n input 



TAPE RECORDER 
GND^ 



PLAYBACK^ 



RECORD 



-oOUTPUT 

AUDIO OSC 
"°GND 



(vtvi 



OGND 



Fig. 1 — Checking frequency response. 



the playback preamplifier, that is, 
before the power amplifier and speaker 
which are built into many home tape 
recorders. Response should be meas- 
ured before the tone control, if any. 
If the tone control is used to obtain flat 
response, it may also be desirable to 
check response for extreme and mid- 
settings of the control. 

Make a tape with an audio generator 
supplying various frequencies at a con- 
stant voltage, say 1 volt, into the re- 
corder, and measure the recorder's out- 
put during playback. Through a switch, 
the same vtvm can be used to measure 
input and output voltages. Record at 
a level substantially (about 20 db) 
below maximum permissible recording 
level as shown by the recorder's level 
indicator — neon lamp, electron-eye tube 
or VU meter. Otherwise a false indica- 
tion of poor high-frequency response 
may be obtained. 

For a quick check at the commonly 
used 7.5-ips speed, frequencies of 50, 
100, 200, 500, 1,000, 2,000, 4,000, 6,000, 
8,000, 10,000, 12,000 and 15,000 cycles 
should be sufficient to obtain a curve. 
On a three-head machine where imme- 
diate playback is available, the play- 
back output may be measured while a 
given frequency is recorded. For ma- 
chines using a single record-playback 
head, all the desired frequencies must 
first be recorded and then played back 
into the vtvm. To recognize frequencies 
during playback, they may be mon- 
itored on an oscilloscope. Or, use brief 
increases in signal level during record- 
ing to mark off several guidepost fre- 
quencies, say 500, 1,000 and 10,000 
cycles. 

In home type recorders, ±3-db re- 
sponse over the range claimed for the 
particular recorder may be considered 
acceptable. The response of profes- 
sional and semiprofessional machines 
should be ±2 db or less over the stated 
range. Be on the lookout for peaks in 
excess of 3 db which sometimes appear 
in the range of 3-8 kc as the result of 
equalization circuits designed to main- 
tain response out to 10 kc and beyond. 
Such peaks, though as low as 3 db, are 
evident to the ear as treble coloration. 

Should frequency response at the 
output of the playback preamplifier be 
within specifications, then the cause of 
poor response lies in later stages. It 
may be in the power amplifier or 
speaker contained in the tape recorder 
or possibly in a tone control circuit 
following the playback preamplifier. 

A frequency response test of stages 
following the playback preamplifier 
may be run by feeding audio frequencies 
to the first of these stages and measur- 
ing output at the speaker voice coil 
with a sensitive vtvm or oscilloscope. 
However, if the internal tone control, 
amplifier and speaker perform normally 
and the customer is feeding the tape 
recorder into a separate amplifier and 
speaker system, apparently his sound 
system is at fault and he should be 
advised to check it by a radio tuner or 
phonograph. 



MAY, 1956 



75 



www.americanradiohistorv.com 



AUDIO — HIGH FIDELITY 

If the tape recorder proper (before 
the internal power amplifier and 
speaker) has poor low-frequency re- 
sponse, the fault is apt to be in a 
defective capacitor or resistor. The 
capacitor may be one used in the bass- 
boost circuit or it may be a coupling 
or screen bypass unit. Most commonly, 
all or most of the bass boost is provided 
in the playback circuit. However, in 
some home tape recorders an equal 
amount is provided in the record and 
playback circuits, as these recorders 
generally use the same preamplifier 
for record and playback. A typical 
playback bass-boost circuit, which 
operates on the principle of shunting 
high frequencies to ground, is shown 
in Fig. 2. If capacitor Cl is open, 




Fig. 2 — Playback bass-boost circuit, 
shorted or substantially lower than de- 
sign value, low-frequency response 
suffers. Similarly, an increase in the 
value of Rl can adversely affect the 
bass end. A feedback type of R-C bass- 
boost circuit is shown in Fig. 3. 




Fig. 3 — Feedback bass-boost circuit. 

If high-frequency response is poor, 
look into the following for the source 
of trouble: 

1. Dirt on heads. As the distance be- 
tween the head and tape, measured in 
1/1,000's of an inch, is increased, 
response drops. The higher the fre- 
quency, the greater the drop. The 
minute separation caused by tape oxide 
deposited on the heads due to friction 
can greatly attenuate high-frequency 
response. Cleaning the head with 
alcohol, using a Q-Tip, is sometimes all 
that is necessary to end the customer's 
complaint. Do not use carbon tetra- 
chloride, it is poisonous and may act 
as a solvent for the head material. 

2. Defective high-frequency equali- 
zation. All or most of the treble boost 
is usually provided in the record pre- 
amplifier. A variety of circuits is used, 
most of them relying upon R-C net- 
works although the use of inductors is 
not uncommon. Fig. 4 shows two typical 
treble-boost circuits, one employing an 
inductor. As in the case of bass boost, 
a defective resistor or capacitor can 
be responsible for incorrect high-fre- 
quency response. 

3. Improper azimuth alignment. This 



fault is most prominent in a machine 
with separate heads for record and 
playback. It is vital that the orienta- 
tion of the record-head gap with re- 
spect to the tape be exactly the same as 
that of the playback-head gap. Each 
gap should be perpendicular to the 
direction of tape travel. Although all 
frequencies are attenuated by improper 
azimuth alignment, the effect increases 
as frequency goes up. In a machine 
which uses the same head for record 
and playback, azimuth misalignment in 
record is compensated by the same 
error in playback. However high-fre- 
quency response results when playing 
back tapes made on other machines, for 
example prerecorded tapes. 

Test tapes are available which per- 
mit rapid azimuth alignment. First the 
playback head is aligned to produce 
maximum output of the high-frequency 
alignment signal on the tape. No further 
steps are necessary for a machine 
using a single record-playback head. 
If a recorder uses separate heads, the 
record head is then aligned so that in 
recording the same high-frequency sig- 
nal the output obtained from the 
aligned playback head is maximum. 

4. Worn heads. High-frequency re- 
sponse depends upon the gap width 
(often called gap length) of the play- 
back head. At 7.5 ips response out to 
10 kc or better requires a gap of .0005 
inch or less. With use, the head may 
wear so as to widen the gap, reducing 
high-frequency response. Because of 
the microscopically small gap, visual 
inspection is of no help and another 
head must be substituted. However, 
before substituting another head, try 
recording a tape on the machine in 
question and playing it back on an- 
other machine of the same brand or 
with similar performance character- 
istics. (Satisfactory recording can be 
achieved with a gap considerably 
greater in length than used for play- 
back.) If high-frequency response is 
still poor and it cannot be corrected 




ihvw 



TO RECORD 



R-C TREBLE BOOST 



TO RECORD HEAD 



L! f3+ 



by azimuth adjustment of the head on 
the machine used for playback, then the 
fault would appear to be in the treble 
emphasis circuit. 

5. Excess bias current. A high-fre- 
quency bias current between 30 and 
150 kc is applied to the record head 
simultaneously with the audio signal, 
its principal purpose being to reduce 
distortion to a satisfactorily low level. 
Up to a point, the greater the bias 
current, the less the distortion for a 
given amount of audio current applied 
to the tape. Beyond this point, an 
increase in bias current fails to reduce 
distortion and may even increase it. 
Unfortunately, long before bias current 
fails to lower distortion, it begins to* 
attenuate the signals recorded on the 
tape. The greater the bias current, 
the greater the attenuation of high 
frequencies as compared to low ones. 
If through failure or change in value 
of a component the amount of bias 
applied to the record head increases 



FROM BIAS OX 



AUDIO SIG IN 




BREAK* 



L-C TREBLE BOOST 

Fig. 4 — Typical treble-boost circuits. 



Fig. 5 — Measuring the bias current. 

substantially over the amount pre- 
scribed by the tape-recorder manufac- 
turer, high-frequency response suffers. 

It is difficult to state the correct value 
of bias current since this differs con- 
siderably among various machines. 
Roughly, in home tape recorders, it 
may range from less than one to several 
milliamperes. The correct value or 
means of determining it should be 
obtained from the manufacturer. Fig. 
5 shows how it may be measured. A 
100-ohm resistor is inserted between 
ground and the ground lead of the 
record head. A vtvm is placed across 
the resistor and the ac voltage is meas- 
ured with the machine in record posi- 
tion but with no signal input and the 
volume control at minimum. 

The bias current is calculated by 
Ohm's law; that is, the measured volt- 
age is divided by 100. If the vtvm does 
not have sufficient sensitivity, a 1,000- 
ohm resistor may be used in place of 
the 100-ohm unit. This results in a 
higher voltage reading. The impedance 
of the record head at the bias frequency 
is usually high enough so that the 
impedance of the 1,000-ohm resistor is 
still low enough to have negligible 
effect upon current through the head. 

6. Slow tape movement. The cus- 
tomer's complaint may be based on the 
fact that old recordings or prerecorded 
tapes sound low-pitched on playback. 
If the tape transport is running below 
rated speed, this reduces pitch. A test 
for speed accuracy can be made by 
determining the time required for a 
tape of known length to run out. Or 
on a machine of known accuracy the 
service technician can make a tape 
with signals at stated intervals, such 
as 1 or 5 minutes, and then use this 



76 



RADIO-ELECTRONICS 



www.americanradiohistorv.com 



these 3 hot dipped galvanized 

towers 
are exclusive with 



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"PACKAGED" 
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For extreme heights and commu- 
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using extra heavy duty tubing and 
corrugated steel cross-bracing is 
utilized in this new Rohn Tower. 
The No. 40 is structurally sound 
so that you can install it for 
heights up to 300'; and is pre- 
ferred for lesser heights when con- 
siderably greater strength is re- 
quired because of excessive wind 
or antenna loading, etc. Check 
this tower for your requirements 
of this type. You'll find it just 
can't be beat, neither structurally 
nor price- wise! 

Note: For lesser heights, use the 
Rohn No. 20 or No. 30 Tower 
, . . for experimental operation, 
use the Rohn "Fold -Over" Tower. 



All Rohn Towers are quickly erected- shipped 
in easy-to-handle sections; and, Rohn-Designed 
accessories are available with each tower. 

Check the complete line of Rohn Towers, including Roof Towers, Masts 
and Tubing . . . plus a full line of tower and TV installation products 
such as bases, house mounts, brackets, service tables, guy brackets and 
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ROHN Manufacturing Company 

I 116 LIMESTONE, BELLEVUE 
I PEORIA, ILLINOIS 



MAIL THIS COUPON FOR FREE LITERATURES 



Rohn Manufacturing Company 
116 Limestone, Bellevue 
Peoria, Illinois 

Gentlemen: Please rush me complete details on the full 
line of Rohn Towers, and Accessories. 



Firm_ 
Name. — . 
Address- 
City„ 



_Titte_ 



_State 



MAY, 1956 



77 



www.americanradiohistorv.com 



Cape Canaveral 

,j0- uunching area 
I cocoa 0\ s 



AIR FORCE MISSILE TEST CENTER 

Florida Flight Test Range 




Q INSTRUMENTATION STATION 
tINE OF FLIGHT 



RCA 



ANNOUNCES OPPORTUNITIES 

In Guided Missile Test Instrumentation 
For Electronic Technicians 

At the following locations 
PATRICK AIR FORCE BASE, FLORIDA CAPE CANAVERAL 



Engineering development technicians 
Radar 

Communications 
Test Equipment 



Radar 
Radio 
Telemetry 



Timing 

Telephone 

Optics 



Enjoy pleasant Florida living and working at these locations. 
Liberal company benefits. Relocation assistance. 

INTERESTING DOWN-RANGE ASSIGNMENTS 

Radar Telemetry Telephone 

Radio Timing Optics 

These positions are located on the Islands shown on the map above. Salary, 
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Technical Employment, Dept. N-15E 

Missile Test Project 

RCA Service Co., Inc. 

P.O. Box 1226, Melbourne, Florida 



RADIO CORPORATION of AMERICA 



AUDIO— HIGH FIDELITY 

as a timing* tape. Or he can purchase 
I one of the Dubbings test tapes which 
I have 5-minute signals as well as other 
useful test material — azimuth align- 
ment, frequency response, maximum 
recording level and signal-to-noise ratio. 

7. Pressure-pad misadjustment. 
Most home tape recorders use pressure 
pads for maintaining good contact be- 
tween the tape and the heads and 
generally provision is made for adjust- 
ing the amount of pressure. Insufficient 
pressure results in reduced high-fre- 
quency response. However, in adjust- 
ing the pad, guard against excessive 
pressure which will increase the deposit 
of tape oxide on the heads, increase 
head wear and possibly decrease the 
tape speed. 

Complete failure to erase may be 
due to the coil in the erase head being 
open or shorted. With the machine set 
for record, check the record head for 
open and short circuits. Erase current 
is often coupled to the record head 
through a resistor or capacitor, and a 
defect or change in value of such a 
component would affect erase. 

Insufficient erase may be caused by 
a dead or weak oscillator. Erase-head 
current in different home recorders 
varies from less than 15 ma to amounts 
several times as great. The actual 
current can be found by connecting a 
vtvm across a 100-ohm resistor inserted 
between ground and the ground lead of 
the erase head and then calculating 
current by Ohm's law. The value so 
determined should be compared with 
that specified by the manufacturer. If 
erase current is more than 20% below 
the required value, oscillator and cou- 
pling components to the erase head 
should be checked. 

Another possible cause of inadequate 
erase is improper vertical positioning 
of the gaps of the record and erase 
heads with respect to each other and to 
the tape. This may occur in some ma- 
chines where the mechanical arrange- 
ment for attaching the heads to the 
transport mechanism permits them to 
be moved slightly up or down. If the 
erase head gap does not fully cover the 
path on the tape covered by the record 
head gap, complete erasure obviously 
cannot take place. On a two-track 
machine, which uses slightly less than 
half the width of the tape for recording 
each channel, it is important that the 
gaps be confined to either the lower or 
upper half of the tape and do not 
extend across the center of the tape. 
Otherwise a portion of each track 
would be reproduced in playback. 

The erase heads on home machines 
often do less than a complete job. On 
tape reuse, the previous recording is 
therefore slightly audible during quiet 
passages. If the owner desires com- 
plete erasure, he should purchase a 
magnetic eraser or one can be eco- 
nomically constructed. (See "Improving 
Inexpensive Tape Recorders," Part II, 
Radio- Electronics, May, 1955, by the 
author.) to be continued 



78 



RADIO-ELECTRONICS 



www.americanradiohistorv.com 



AUDIO— HIGH FIDELITY 



FOR 




ONLY 




The Heath kit AG-9 } audio generator; 
Knight SX702 AM-FM-TV 
tuner; Cahinart accessories; 
Ortho-Sonic tone arm 

By MONITOR 



ONE of the most tedious lab- 
l oratory and servicing proce- 
dures is making a series of 
frequency runs with an audio 
generator. Those who have to do this 
frequently will find the Heathkit AG-9 
an extremely clever new instrument. 

The innovation is the tuning method. 
Instead of continuous tuning, the AG-9 
uses three switches which provide two 
significant figures and a multiplier. 
The combination covers the range from 
10 to 100 in units of 1 cycle, from 100 
to 1,000 in units of 10, from 1,000 to 
10,000 in units of 100 and from 10 to 
100 kc in units of 1,000 cycles. Super- 
ficially it might seem that this would 
be more complicated than using a single 
continuous-tuning dial and a range 
switch. But when one has become accus- 
tomed to it, it is possible to make a run 
in a fraction of the usual time and 
with considerably greater accuracy be- 
cause it takes a fraction of a second 
to flip a switch but several seconds to 
readjust a dial accurately to a new 
frequency. It is possible that there are 
some applications in which the ability 
to cover a range continuously and with- 
out any skips or steps is desirable. But 
the steps here are in terms of 1% of 
the frequency and in audio it is prac- 
tically impossible to obtain resonant 
peaks or nulls that sharp. 

The usefulness and accuracy of the 
generator (see diagram) are further 
improved by the output meter which 
monitors the output in terms of volts 
or db. Most service type generators 
have an amplitude error of 1 or 2 db 
from one decade to another or from one 
end to the other of the same decade. 
One either has to remember the error 
and correct for it or use an external 
meter if greater accuracy is necessary. 
With the AG-9 it is possible to keep the 
output constant. The overall accuracy 
over the full range from 10 to 100,000 
cycles appears to be well within 1 db, 
and within the 20-20,000-cycle range 
it is better than that. 

The output is controlled by a combina- 
tion of a potentiometer and a decading 
attenuator in eight voltage ranges with 



a maximum of 3 millivolts on the lowest 
range and 10 volts on the highest. The 
leakage is very small and the minimum 
voltage on the lowest range is less than 
100 /*v. Thus, the generator can be fed 
into the most sensitive preamplifiers 
without overloading. On the 3- and 10- 
volt ranges the source impedance is 
around 1,000 ohms; the lower ranges 
can either work into a 600-ohm external 
load or a 290-ohm internal load is 
available through a switch. 

The AG-9 uses the now well known 
Bureau of Standards circuit with res- 
onance controlled by a T network in a 
feedback loop. Critical component toler- 
ances are 1% for resistors and 2% for 
capacitors. The construction is simple 
and the adjustment even simpler. Only 
the meter requires calibration and for 
normal useage the heater voltage is 
sufficiently accurate for a standard. 

Fig. 1 shows the T network (within 
the dashed lines) with a set of codes. 
Actually, capacitors Cl and C2 repre- 
6CL6 6X4 



sent four pairs that are switched into 
the circuit by turning the multiplier to 
its four positions. Resistors Rl and R2 
represent 10 sets of resistors that are 
switched into the circuit. 

Knight SX702 AM-FM-TV tuner 

The Knight line of high-fidelity equip- 
ment has always provided high quality 
per dollar and the SX702 tuner is an 
example of more of the same. The 
usable FM sensitivity is* surpassed only 
by two or three of the highest-priced 
tuners, but the difference may be en- 
tirely academic unless in your location 
a 3-6-db increase in gain is just what 
is needed to shove a station over the 
noise threshold. In my location the 
sensitivity was adequate to provide 
acceptable reception of all but the very 
weakest of the stations regularly re- 
ceivable with the best receiver tried 
so far. The biggest difference is that 
very weak stations (which will not 
saturate the limiters of any tuner) are 



117 VAC 




® SCREWDRIVER ADJ 



Schematic diagram of the Heathkit 
audio signal generator model AG-9 



MAY, 1956 



79 



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RADIO • TELEVISION ♦ INDUSTRIAL ELECTRONICS 

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For beginners, this giant hook 
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Here are just a few of the sub- 
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lems ; Servicing Communications 
Receivers ; a Complete Guide to 
Television Service ; AM, FM, and 
TV Realignment Made Easy ; Re- 
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I HI JH io & TV TROU- |—| Radio & TV CIRCUI- 
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AUDIO— HIGH FIDELITY 

less readable in the noise. One or two 
of the new wide-band-detector tuners 
have lowered distortion but whether 
this makes a practical difference in 
overall distortion will depend on how 
careful the broadcast stations are in 
holding down their own distortion. 
There is a choice of tuning* with or 
without afc. A meter and a good dial 
ratio result in uncritical tuning. 

The AM characteristics with the 
built-in ferro-loopstick antenna are 
very good and in most locations no 
additional antenna is needed. The band 
width appears to be about 10 kc and 
provides excellent reception with low 
interference in secondary and fringe 
areas ; for local use the frequency 
response is narrower than desirable. 

The unique feature of the Knight 
(shared also by the Rauland line) is the 
availability of a TV-sound tuner which 
can be plugged in as an accessory. This 
will provide TV sound almost infinitely 
superior to that of the best available 
TV receiver and greatly superior to 
that possible when the sound output of 
a TV receiver is fed into a high-fidelity 
outfit. The fine reception is possible 
because there is no difficulty with inter- 
ference from the sync frequencies and 
the if channel of the Knight tuner 
provides very wide bandwidth com- 
pared with that of a good TV receiver, 
reducing distortion to about the same 
degree as the wide-band FM tuners 
reduce it on the FM band. TV sound 
is beginning to improve and some of 
it qualifies for high-fidelity standards; 
in any case, the improved sound quality 
greatly improves the illusion of presence 
and versimilitude. 

Moreover, I have found that many 
TV programs are just as enjoyable 
with sound alone and this way provide 
far less distraction for other activities. 
Finally, those in the extreme TV fringe 
areas can improve their overall TV 
reception by using this separate TV 
sound tuner; the TV receiver can be 
tuned for peak picture reception and 
the sound tuner for best sound. The 
TV tuner consists of a Standard Coil 
tuner remodeled to provide a 10.7-mc 
if output. 

The audio output of the Knight tuner 
I is very good indeed. Two outputs are 
| provided from a cathode follower for 
amplifier and tape recorder. An un- 
usual feature of the Knight is that 
there is no volume control on the panel. 
The level of the amplifier channel can 
be set by a potentiometer on the rear 
of the chassis. The idea is that the 
volume will be controlled by the control 
unit. 

Phono accessories by Cabinart 

It has been well said that some of 
the best things come in very small 
packages. A case of hi-fi point is the 
Levelor kit introduced by Cabinart. 
Why nobody thought of putting some- 
thing like this out before I do not know. 
Certainly Cabinart deserves a medal 
for making it available. The Levelor 
is simplicity itself. It contains a bubble 



80 



RADIO-ELECTRONICS 



www.americanradiohistorv.com 




BALLAST RESISTORS 
FUSE-TYPE RESISTORS 
LINE-VOLTAGE REGULATORS 

CLAROSTAT resistance devices are designed to 
meet your needs in radio and television servicing. 
Voltage regulators serve as safeguards against line-voltage 
surges, and are popular, essential accessories. 
Ballast tubes serve as fuses in many television receivers and are 
expendable, easy-to-replace components. 
Fuse-type resistors are being used by television receiver manufacturers 
and should be on every serviceman's parts list. 
Get the complete story on these CLAROSTAT products designed 
to fill your needs, from your distributor. 

CLAROSTAT MFG. CO., INC., DOVER, NEW HAMPSHIRE 

In Canada: Canadian Marconi Co., Ltd., Toronto, Ont. 

MAY, 1956 




81 



www.americanradiohistorv.cam 



AUDIO— HIGH FIDELITY 




The Hard Ortho-Sonic pickup arm. 



level which can be mounted on top of a 
changer or turntable base and which 
indicates precise leveling- in both dimen- 
sions at a glance. Having determined, 
as you are certain to, that the base is 
out of level and the pickup arm compli- 
ance is being fouled up by gravity, the 
next problem is to correct matters. 
Therefore, the kit contains four rubber 
feet to fasten to the bottom of the 
turntable or changer base. But these 
are not ordinary feet — each has a screw 
which permits an adjustment in length 
(and therefore in height of base) of a 
little over *4 inch. With one on each 
corner of the base, it should be possible 
to make a turntable level even aboard 
a yacht. In the average installation 
you'll recapture the $2 cost of the kit 
in a mere week, in the form of less 
damage to your prized records through 
groove jumping, skipping and skating, 
as well as in more satisfactory sound. 

To make putting a hi-fi together 
easier, Cabinart also has several other 
items. The ACC-1 record change r or 
turntable base is a tray made of birch 
plywood with a top precut for any of 
the popular changers or turntables; the 
whole is mounted on excellent quality 
ball-bearing slides. The slides can be 
mounted on a shelf or in a cabinet in 
a jiffy and you have a professional 
slide-out changer for a minimum of 
labor and a cash outlay of just $10. 

The ACC-2 is a handsome base (with- 
out slides) for professional type turn- 
tables. It is made of heavy plywood 
with genuine mahogany, walnut, korina 
or ebony black lacquer finish. The top 
is available either precut for any of 
the standard turntables or in one solid 
piece for cutting by the customer. An 
interesting and very helpful design 
feature is that the top floats on a 
sponge-rubber gasket to minimize the 
bad effects of vibration and shock. The 
base is large enough for any turntable 
I know of including the D & R and 
still leaves plenty of room for a tran- 
scription type arm. 

In addition Cabinart has a series of 
partitioned lightweight record storage 
units ranging from 1 to 3 feet long and 
in price from $9 to $25, and a series 
of wrought iron bases for each. 

Ortho-Sonic tone arm 

Ever since the cylinder record was 
abandoned in favor of the disc, play- 

82 



back has suffered from the tracking 
error which results because the cutting 
stylus moves in a straight line across 
the radius of a disc, whereas a play- 
back needle — on its arm pivoted outside 
the diameter of the disc — moves in an 
arc. So the playback needle can repro- 
duce the exact movement of the cutting 
needle at only one point (at best) and 
at all others departs from the ideal 
alignment by up to 25°. For years 
engineers have been trying to produce 
a playback mechanism which would 
reproduce accurately the movement of 
the recording equipment. 

The Otftho-Sonic V/4 has some minor 
faults but does solve the essential 
problem of eliminating tracking error. 
Since the needle now follows the same 
straight line path as the cutting needle 
there is no tracking error at all. The 
benefit from this should be lower dis- 
tortion, and my measurements — though 
not of laboratory conclusiveness — indi- 
cate that the benefit is achieved. With 
ordinary arms there is some variation 
in IM distortion as the arm moves from 
outside to inside of the record; in the 
Ortho-Sonic the variation is consider- 
ably less. (Unfortunately, variations in 
distortion from outer to inner diameter 
can be due to other causes, even in the 
recording process, and it is not possible 
completely to isolate the portion due to 
tracking error only. But so far as I 
can determine the aberrations due to 
tracking error are at least greatly 
minimized and possibly eliminated.) 

Granting this, the real test comes in 
that other type of tracking — the ability 
to follow high-amplitude modulation of 
the groove without skipping, jumping, 
groove locking or loading the needle. 
To distinguish it from tracking error 
I will refer to it as arm compliance for 
in essence it represents the ability of 
an arm to permit the needle to comply 
with the motion imparted to it by the 
grooves without loading that motion 
with its own friction or mass. The 
trouble with past attempts at solving 
the tracking-error problem has been 
that the suspension has had so much 
friction that the loading of the needle 
produced effects far worse than the 
tracking error did. In this respect the 
Ortho-Sonic seems to be superior to 
most conventional arms. It will pass 
the Mc Proud test which consists of 
placing a big-hole 45-rpm disc on a 



table so that one edge of the hole is 
against the center pin. This imparts 
an eccentric motion to the arm with a 
swing of more than 1 inch. The Ortho- 
Sonic will track this way without skip- 
ping, jumping or locking about as well 
as any other arm I know of. Since the 
eccentricity of the McProud test is a 
gentle one resembling a sine wave, it 
is not as severe as that produced by 
extremely sharp high-amplitude tran- 
sients recorded in a normally revolving 
groove because the sharp transients 
"throw" the arm more sharply and im- 
part higher velocity. Many arms which 
meet the McProud test will nevertheless 
fail on such recorded transients, as 
those on Cook's Earthquake or Audio- 
philes Thunder storm. So far as I can 
determine the Ortho-Sonic is just below 
the Ferranti, which in this respect is 
the best of all arms tested. At any rate, 
in some months of use it has not been 
guilty of skipping or locking once. 

It seems to be at least as free of 
resonances as conventional arms. This, 
I guess, is the result of the fact that 
the cartridge mount is isolated from the 
large superstructure of the arm through 
friction-free bearings. It is easy to 
install and equally easy to adjust for 
height, needle pressure and parallelism 
to the disc, and no more sensitive to 
leveling. It has features conventional 
cartridges do not possess. There is an 
indexing scale with a magnifier which 
enables one to index records and place 
the needle quite accurately in the de- 
sired groove. Cueing is even more 
accurate. The record can be precued 
with the needle in the groove and 
stopped exactly in the desired spot ; 
when the arm is lifted with only reason- 
able care and then returned to the 
groove, the exact same spot can be 
found very accurately. Radio stations 
should find this a worth-while feature. 

There are some disadvantages, the 
most serious of which could be corrected 
by refining the design. The cartridge 
mount is of the slide-in type with a 
knurled knob to fasten the cartridge 
in place. Unfortunately, this design 
will not accept all available cartridges 
by any means; in fact, the cartridges 
it will take without providing special 
mounts constitute a minority of those 
on the market. It will take the G-E 
(either turnover or single) Fairchild, 
the original Pickering and the indi- 
vidual units of the 240 series. But most 
of the others will require some addi- 
tional mount which I presume the 
manufacturer will soon make available. 
The arm is a little more awkward to 
use initially, but once a habit is formed, 
this disadvantage disappears. I have 
not tried all possible mounting posi- 
tions but I judge that for accuracy in 
letting down the needle and using the 
indexing scale, it will have to be put 
somewhere on the right of the turn- 
table, whereas conventional arms per- 
mit a greater choice of position. But, 
assuming you can mount your favorite 
cartridge in the Ortho-Sonic, the minor 
faults are petty in relation to the 
virtues. END 

New Records Review is on page 102, 

RADIO-ELECTRONICS 



www.americanradiohistorv.com 



ELECTRONICS 



RADIO-FREQUENCY LAMP 



By S. C. PEEK* 



THE high-frequency oscillator shown 
on the cover is designed to power 
the brightest incandescent lamp 
ever sold commercially. The light 
source is a solid disc of tantalum car- 
bide heated inductively by the output 
from the 3.5-mc oscillator. 

Early incandescent lamps had carbon 
filaments, but these lamps could be run 
at relatively low brightness only, be- 
cause of the rapid rate of carbon evap- 
oration. Tungsten provided a means 
of obtaining much greater brightness 
and has been used ever since. The past 
50 years have seen no radical change 
in incandescent filament structure but 
recent developments-, in color TV, wide- 
screen movies and fast-thinking com- 
puters have emphasized the need for 
an even brighter incandescent lamp. 
These applications also demand more 
uniformity in the light source than can 
be obtained from a coiled filament. 
Radio-frequency heating of a tantalum 
carbide disc provided the answer. The 
oscillator and lamp were developed by 
Sylvania Electric Products Inc. 

The light source is a 5/16-inch- 
diameter disc of tantalum carbide sur- 
rounded by a silver-plated copper 
cylinder which concentrates the mag- 
netic field right at the disc. The oscil- 
lator tank coil is placed around the 
lamp, closely coupled to the copper 
cylinder (Fig. 1), Therefore, in effect, 
the tantalum carbide disc becomes the 
final sink for most of the radio-fre- 
quency power generated by the oscil- 
lator. Since the eddy currents developed 
by the alternating magnetic field pro- 



TANTALUM CARBIDE 
(TARGET) 



WATER COOLING 
TUBES 




♦Sylvania Electric Products Inc., Salem, Mass. 



COPPER 
CYLINDER 
(CONCENTRATOR) 



duce circular currents in the disc, 
heating is uniform and symmetrical. 
Therefore, the light produced by the 
incandescence of the disc is uniform 
across its entire surface. Furthermore, 
tantalum carbide has such a high melt- 
ing point and its rate of evaporation is 
so low that it can be heated to a very 
high temperature (3,400° C). This pro- 
duces twice the light per square milli- 
meter of surface area than in any 
known incandescent lamp and lasts five 
times longer as well. Water-cooling 
tubes are inserted through glass-to- 
metal seals in the base of the lamp. The 
tubes are attached to the copper cyl- 
inder and keep it cool. Were it not for 
water cooling, the tremendous currents 
would melt the copper. 

T]je radio-frequency source consists 
of two 833-A triodes (Fig. 2) operated 



Cutaway view 
of the rf lamp. 



as a self-excited push-pull oscillator. 
A 15-turn copper-tubing tank coil and 
a 350-M/"f vacuum capacitor provide a 
parallel-tuned tank circuit resonant at 
approximately 3.5 mc. Bypass capac- 
itors and rf chokes prevent the dc plate 
voltage from appearing on the tank 
coil. This arrangement produces a 1.5- 
kw output with all components operated 
well within their ratings. 

A separate dc supply powers the 
oscillator. It operates from a 230-volt 
60-cycle 3-phase line and uses six 866- 
A's in a bridge rectifying circuit. The 
use of a 3-phase power supply makes 
filtering unnecessary and provides 4,000 
volts at 1 ampere for plate power. 
Varying the voltage with a variable- 
voltage transformer provides control of 
the lamp brightness. 

Both power supply and oscillator are 
completely shielded and rf filters are 
placed in the power-line connections, 
keeping the radiation well under 10 
microvolts at l / 2 mile from the installa- 
tion, to prevent interference with radio 
or TV reception. 

Although the lamp was originally 
designed for motion-picture printing, it 
has found its way into some interest- 
ing electronic applications — color pic- 



UGHT-EMITT1N6 TARGET 

OPTICALLY FLAT- 



OSCILLATOR 




GLASS ENVELOPE 



WATER COOLING TUBES 



Fig. 1 — Diagram of rf lamp system, 
MAY, 1956 




TO BLOWERS FOR 833-A'S 



Fig. 2 — Schematic diagram of power supply and oscillator for rf lamp. 



83 



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depend upon a 
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ELECTRONICS 

ture-tube processing, 
outs and instrument 
beam checkers. 

Color picture tubes 
photographic process 
three-color dot clusters which make up 
the light-emitting surface. In the fin- 
ished tube an electron beam will pass 
through small holes in the aperture 
mask and excite one of the three colors. 
It is essential for good color reproduc- 
tion to have the proper color phosphor 
dot precisely aligned with respect to 
the aperture mask holes and the elec- 
tron gun. The light beam which exposes 
the photo-resist phosphor and also 
determines its position must follow the 
same path as will the electron beam in 
the finished tube. The light beam must 
therefore come from a concentrated 
source approximating the dimensions 
of the electron beam at its origin. The 
rf lamp not only provides the necessary 
concentrated source but also greatly 
speeds up the process because of its 
high brightness. Although there are 
still other costly processes in the manu- 
facture of color tubes, the rf lamp has 
a good chance of significantly reducing 
the cost of an important one. 

The rapid advances in electronic com- 
puters have resulted in a peculiar 
dilemma. They can think faster than 
they can talk! Computation and refer- 
ence to data in their memory is limited 
only by the speed of an electron in a 
vacuum tube or the migration of a hole 
in a transistor, but communication of 
the results to the outside world has 
generally depended upon some slower 
mechanical device. Recent develop- 
ments in the readout or communicating 
section have made use of a combination 
of light beam, electron beam and photo- 
graphic emulsion. All these phenomena 
are fast especially if the light beam is 
bright. The rf lamp looks very promis- 
ing for this application and speeds of 
10,000 digits or letters per second may 
soon be realized. 

Still another use may be connected 
with electronics in aviation. The high- 
frequency ILS beam used to guide air- 
craft in for a landing sometimes drifts 
from its desired position, a very serious 
situation. Present methods for checking 
the position of these beams is time- 
consuming and costly. A light beam 
does not stray from the path upon 
which it is directed and, therefore, 
might be used as a reference beam 
which a pilot could use in good weather 
to check the radio beam. The problem 
was to get a sufficiently narrow light 
beam, bright enough for good visual 
tracking. The rf lamp has character- 
istics which seem to solve this. 

Thus, one more industry — illumina- 
tion — is being advanced through elec- 
tronics. Communications and the enter- 
tainment fields have blossomed because 
of electronics. Aviation would be lost 
without it and now even lighting is 
feeling the impact of this powerful, 
ever-expanding conglomeration of tubes, 
wires, capacitors, coils, transistors and 
heaven knows what else. end 

RADIO -ELECTRONICS 



www.americanradiohistorv.com 



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85 



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CONTROL 

UNIT 
FOR 

VENTILATING 
FANS 



By ELLIOTT 
A McCREADY 



P*»nel view of 
the control unit. 



VENT HOLES 



Right — Internal view 
shows layout of parts. 



■ 






RE LAV 



2051 



POWER TRANS 



Above — The outside 
temperature-sensing ele- 
ment is in ventilated, 
weatherproof case. 



THE attic ventilating fan is becom- 
ing almost standard equipment 
in many new (and older) homes. 
On warm summer evenings it ap- 
proaches air conditioning by exhaust- 
ing the hot air from the house and 
replacing it with much cooler outside 
air — a process which might take all 
night without such a fan, depending 
on the amount of breeze. 

The ventilating fan has one major 
disadvantage: it must be switched off 
in the morning as the sun rises. Failure 
to do so will defeat the purpose of the 
fan by filling the house with warm air. 
This disadvantage can be overcome by 
any of several methods. You can set 
the alarm clock and risk a fractured 
toe stumbling out to switch the fan off 
or you can buy an electric timer to do 
the job for you. The alarm-clock method 
is obviously a pain in the neck. The 
timer isn't too good either because it 
must be properly set each night and a 
sudden rise in outside temperature will 
raise the temperature of an already 
cool house. 

The ideal method of controlling the 
ventilating fan would be by tempera- 
ture differential — as long as the inside 
temperature is the same as, or a preset 
amount above, the outside temperature, 
the fan should be off. When either the 
inside temperature rises or the outside 
temperature falls, the fan should switch 
on. If the outside temperature should 
start to rise, the fan should remain off. 
This type of control sounds like a 
pretty large order but it's really simple 
and relatively inexpensive to build. 

Two temperature-sensitive elements 
THERM1 and 2 form the heart of the 
control unit. These are two Carboloy 
type Rill thermistors with a resist- 
ance of about 100,000 ohms at room 
temperature and a very large negative 
temperature coefficient. These thermis- 
tors are available and information 
regarding prices may be obtained by 
writing Carboloy Dept., General Elec- 
tric Co., Detroit 32, Mich. 

The thermistors act as a voltage 
divider across a variable dc supply. 
The grid of the 2051 thyraton is 
connected to the midpoint of this volt- 
age divider and any change in temper- 
ature at either the inside or outside 
sensing element will raise or lower the 
bias on the tube, opening or closing the 



RADIO-ELECTRONICS 



www.americanradiohistorv.com 



.5 „600V_ 




THERM I THERM 2 
(OUTSIDE) (INSIDE) 



ELECTRONICS 

relay. Using an ac plate supply enables 
the grid of the thyratron to regain 
plate control on the negative hal re- 
cycles of plate voltage. Resistor R2 
limits thyratron grid current to an 
optimum value. The large resistance 
in the grid circuit stabilizes the unit 
against changes in grid current pro- 
duced by widely varying outside and 
inside temperatures (and subsequent 
changes in the total resistance of the 
voltage divider). 

A relay with an ac coil permits 
manual operation of the fan without 
using a hefty switch. Current-limiting I 
resistor R3 was made adjustable to 
minimize relay stuttering. The value 
shown in the schematic was found best 
for smooth relay operation and max- 
imum temperature sensitivity. 

Construction and operation 

The unit was built in a 6 x 9 x 5-inch 
utility cabinet. All components were 
mounted on the front panel as shown 
in the photo, and two Cinch-Jones 
terminal strips and. spade lugs make 
it easy to remove the unit. The cabinet 
was fastened to the wall and the power, 
fan and thermistor lines run through 
the wall and into the rear of the cabinet. 
Ventilating holes were drilled on either 
side of the cabinet, but the unit runs 
very cool and only a few holes are 
necessary. Parts placement isn't crit- 
ical. 

The temperature-sensitive elements 
are mounted one inside and one outside 
the house (don't get the leads mixed). 
The outside element is best situated on 
the north side of the house in a ven- 
tilated, weatherproof case (see photo). 
I found a surplus generator shunt case 
which proved ideal. The inside element 
is mounted in a room which is in the 
air path between the fan and an open 
window. 

When the unit is connected, turn the 



Schematic diagram of control unit. Two 
thermistors make up voltage divider. 




WHITE DOT GENERATOR 
model 434 




iographx) 



Provides white dot patterns with VARIABLE dol size (from 1 to 8 scanning lines; 
with corresponding dot widths), and variable dot number from 6 to 12 horizon- 
tal dots, and 6 to 1 2 vertical dots. Modulated RF output is available, operating 
on fundamentals from Channel 2 to Channel 6. 

THE ONLY WHITE DOT GENERATOR THAT LETS YOU 
MATCH ANY RECEIVER MANUFACTURERS' RECOMMENDATIONS 



You can make convergence ad- 
justments on color-TV receivers 
faster and better with the new 
Simpson Varidot. Use for linearity 
adjustments on both color and 
black and white. 

Vertical and horizontal syn» 
chronization assures you of correct 
aspect ratio . . . ample attenuation 
... 300 ohm RF output. 

Adjustable dot size provides a 
check of receiver transient re- 
sponse. Positive or negative video 



output is excellent for accurate 
and fast checking of transient re- 
sponse of video amplifiers. 

Use the new Simpson Varidot 
for hum checking both color and 
black and white receivers — a rare 
feature in test equipment at this 
price. 

Portable: Approx. 11% lbs. 
Housed in Simpson gray case, 

50 



Complete with Output Cables 
and Operating Instructions 



See Your Electronics Paris Distributor, or write 



MAY, 1956 



W»RUTS EARNEST MANUFACTURER 

OF IUC1TR0NIC TEST EQUIPMENT 



5200 W. Kinxte $\j Chicago 44,llHncisf 
r I r^TDl/ 1 fA II V Phone: EStebrook 9-1 121 

ELECTRIC CO Mr AN I fn Concur Bach-Simpson Ltd., London, Ontario 



www.americanradiohistorv.com 




ELECTRONICS 




E 8 | 
J*° 9 

>• * a . 

0) «- Q- C 

c a> — o 

uo O 0) O 

ill k 

I! w « 

*~ 2 Z 

O X C 4> 

c > o o 



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< ° 

: * 1 1 

1 in 

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Z Oc D 

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2 > 
* - •- "° 



selector switch to AUTO and set R3 for 
minimum bias for the 2051. After the 
unit warms up, the fan will switch on. 
Let the fan run for a couple of hours 
until the temperature in the vicinity 
of the inside sensing element stabilizes. 
Then slowly back off R3 until the fan 
switches off. The unit is now set. 
Slight additional adjustments may be 
necessary but once the unit is set it 
is very stable. Future use of the unit 
requires about a half-hour for the cir- 
cuit to stabilize, but no adjustment of 
the temperature control is necessary. 

If the relay tends to stutter slightly 
before making, increase the value of 
Rl slightly. If the unit seems insensi- 
tive to temperature variations, decrease 
Rl. When the unit is properly adjust- 
ed, room temperature should be constant 
within 1 or 2 degrees (decreasing as 
the outside temperature decreases). 

An advantage in using this control 
unit that may not be immediately 
obvious is the fact that the fan doesn't 
run continuously. The saving in elec- 
tricity and wear and tear on the fan 
motor should help pay for the unit. 

After reading this far, a few ques- 
tions may have come to mind: For 
instance, what happens if the control 
unit switches the fan on when all the 
windows and doors are closed or a 
sudden shower at night lowers the out- 
side air temperature and switches the 
fan on, sucking in all kinds of water? 



Parts for control unit 

I — 100.000 ohms, I — 4.7 megohms, '/j-watt resistors; 
I — 50-ohm wirewound potentiometer; I— 2,000-ohm 
10-wdtt adjustable resistor; I — 0.25 uf (200 volts), 
1—0.5 (600 volts), 8 *if (450 volts) capacitors; 
I — power transformer, secondary 1 1 7 volts at 50 ma, 
6.3 volts at 2 amps (Merit P-3045 or equivalent); 

1 — power relay, 1 15- volt coil, spdt (Potter & Brum 
field MR5A, 115 volts, or equivalent); 1—2051 thyra- 
tron and socket; l—65-ma selenium rectifier; I — 
4-pole 3-position rotary switch; 2 — thermistors, Car- 
boloy type RIM or equivalent; I — 9 x 6 x 5-inch util- 
ity cabinet; 2 — Cinch-Jones type 6-140 barrier strips; 

2 — containers for thermistors (see text); I — knob. 

Obviously, even with the control unit 
added, the ventilating fan is not an air 
conditioner and its use is confined to 
those evenings when there is insufficient 
breeze to cool the house or when the 
breeze is coming from the wrong direc- 
tion. Most people like to have the 
windows and doors open on a warm 
summer day. I switch the control unit 
off altogether when I get up in the 
mornings and thus the chance of the 
unit switching on with the windows 
and doors closed is remote. 

Now for the rain problem. Since 
most summer showers are accompanied 
by a westerly breeze, I use east win- 
dows as an air inlet. I have found that 
very little rain is sucked in by the fan 
if the open window is on the downwind 
side of the house. Incidentally, I have 
never yet failed to waken when it 
started to rain at night — fan operating 
or not. I think that if one of the open 
windows is located in the master bed- 
room, very little trouble should be 
encountered with showers. A moisture- 
actuated switch connected to the con- 
trol unit and located near the window 
would remove this problem. end 

RADIO-ELECTRONICS 



www.americanradiohistorv.com 



OF 



THE 

TURRET STYLE TUNER 

OF THE 

STANDARD CASCODE TUNER 



OF THE 

STANDARD PENTODE TUNER 

NEW NEUTRODE TUNER 

WORLD'S LARGEST MANUFACTURER 
OF ELECTRONIC COMPONENTS 




STANDARD TUNERS have been used in 
more than 19,000,000 TV receivers and designs 
contributed by STANDARD to the industry 
hafve been used ior many millions more. 
STANDARD has not only a tremendous 
engineering department for production and 
development but also one of private indus- 
try's largest pure research engineering staffs 
foB electronics. Only recently STANDARD at 
symposiums attended by all major TV manu- 
facturers exposed the results of several inten- 
sive years of color TV research— results 
which will reduce by several years the time 
required for the development of practical 
color TV. 

Floneers in Universal Replacement Tuners for TV 
Originators of Packaged Tuned Circuits 



STANDARD PRODUCTS ARE WIDELY VARIED 



for the full story write or phone: C. A. Swanson, General Sales Manager 
Standard Coll Products Co., Inc., Melrose Park, Illinois 



Coil Products Co., Inc. 

six plants: Chicago • Los A.igeles • Bangor, Mich. 
North Dighton, Mass. 

Kolllsman Instrument Co. wholly owned subsidliary 



MAY, I956 



89 



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ELECTRONICS 



SERVICING THE 

WATCHMASTER 

By JACK DARE 



FOR the benefit of those service tech- 
nicians who have never run into 
one, the Watchmaster is an elec- 
tronic device used for accurately 
testing* and adjusting* watches. It en- 
ables a watch repairman to listen to 
amplified sounds of a watch movement 
and make a permanent record (Fig. 1) 
of the actual gain or loss of time. With 
this machine, variations as little as 
1 second per day can be detected. The 
line of dots traveling straight across 
the paper indicate a watch that is 
keeping perfect time; the upward- 
sloping* line a watch that gained; the 
downward-sloping line a watch that 
lost. Each fine line indicates 1 second, 
each heavy one 5 seconds. 

Driving power for the motor is sup- 
plied by a 240-cycle tuning-fork oscil- 
lator, a 4-to-l frequency divider and 
a power amplifier. (See Fig. 2.) VI is 
the amplifier-oscillator. The fork vi- 
brates and induces a voltage in the out- 
put coil. This voltage is amplified by 
Vl-a and Vl-b. A part of the output 
of Vl-b is fed back to the driving coil 
of the fork to sustain its vibrations. 
The output of the amplifier circuit is 
held constant by the Varistor in the 
negative feedback loop. The resistance 
of the Varistor varies inversely as the 
voltage applied to it. Thus, when the 
fork's output is low, the feedback volt- 
age reaching Vl-a's cathode is low and 
the stage gain is high. As the fork's 
vibrations increase in amplitude, the 
input and output of VI tends to rise 
accordingly. However, the Varistor acts 
as a variable resistor in the feedback 



ad 



Os- 



good 

WATCH 



Fig, 1 — Diagram shows typical chart 
made on rotating drum of Watchmaster. 

90 



path to keep the output of VI and the 
fork constant. 

The output of Vl-b is also fed to V2, 
a multivibrator that divides by 4 to 
reduce the signal frequency to 60 cycles. 
The 60-cycle signal is amplified by V3 
and applied to the motor through an 
output transformer. Motor voltage is 
around 110 but can drop to 100 without 
serious loss of speed. 

The resistors marked with asterisks 
are especially selected values that 
determine the amount of feedback and 
the multivibrator's frequency. These 
values vary between individual units. 

Beneath the recording drum is an 
electrically driven stylus coupled to a 
half-nut drive. This moves the stylus 
along the drum, taking 30 seconds for 
the full length. A snap-action switch 
disconnects the motor at the end of 
travel. The sound of the watch-ticks 
is picked up by a small crystal micro- 
phone (Fig. 3) mounted in the watch- 
holder on the right side of the machine 
(see photo). The output of this pickup 



AMPl.OSC 



is fed to a two-stage amplifier using 
6SJ7's. Amplifier gain is controlled by 
a 50,000-ohm potentiometer connected 
across the pickup. 

The amplifier feeds a 2050 thryiatron 
which drives the coil of the recording 
stylus. Each impulse causes the stylus 
to snap upward, making a dot on the 
chart, through a tape similar to a type- 
writer ribbon although wider. In the 
grid circuit of the 2050, a dpdt KECORD- 
Listen switch connects the output of 
the amplifier either to the grid of the 
thyratron and the recorder or to a 
single earphone. 

Servicing these machines should not 
be difficult for any radioman. All tubes 
used are standard receiving types with 
the exception of the 2050 and VR150, 
and these are readily obtainable. Most 
of the troubles found will be in weak 
or dead tubes. 

The ac type power supply uses a 
5U4-G with a simple choke-input pi 
filter. The first capacitor, an 8-vf, 600- 
volt unit, is visible immediately behind 



6L6-G 

PWRAMPL 




Fig. 2 — Schematic shows circuitry of fork, frequency divider and amplifier. 



SOO^f 



JOOnnf 6SJ7 



XTAL 
MIKE 




Fig. 3 — Schematic shows circuitry of 
amplifier and the recording stylus. 



RECORD 
— f PHONE JACK 



RADIO-ELECTRONICS 



www.americanradiohistorv.com 



ELECTRONICS 



Underchassis view 
of the Watchmaster. 



the recording drum. The other filters 
are plug-in types. 

If the motor will not run, check the 
fuse, rectifier, voltages, the two 6SN7's 
and the 6L6. If the tuning fork is 
running, the vibration may be felt on 
the housing. If it is not running, check 
the leads at the bottom of the case for 
breakage. The case is shock-mounted 
and movement sometimes breaks these 
wires. The snap-action switch actuat- 
ing lever sometimes becomes damaged, 
as does the switch itself. 

If the unit runs but does not record, 
turn the switch to listen and check the 
amplifier. If the sound is coming 
through the amplifier, check the stylus 
coil for continuity. This unit has two 
long and very flexible leads to enable 
the stylus to travel; these have been 
found open. 

The record-listen switch is a toggle 
type and subject to trouble from dirty 
contacts. It closes the cathode circuit 
of the 2050 in the record position and 
may not be making good contact, caus- 
ing erratic operation of the recorder. 
It is a good idea to wash this switch 
with contact cleaner each time the 
machine is brought in for service. 

The gain control is a 50,000-ohm 
unit and may cause noise or erratic 
operation if it becomes dirty. Wash 
with cleaner or replace if too noisy. 
If this unit opens entirely, it will cause 
the amplifier to hum and become un- 
stable, making very peculiar record- 
ings. Sometimes the amplifier will 
sound as if it were motorboating. If 
bridging filter capacitors does not help, 
check to see if the driving-current im- 
pulses from the fork and oscillator 
circuits are being picked up by the 
amplifier. This pickup generally occurs 
in the first stage and gain-control cir- 
cuit. 

Although all these leads are shielded, 
check the grounding carefully. Adding 
an extra ground lug at the gain control 
usually aids in eliminating this pickup. 
If some noise remains, try adding an 
extra 0.1-/if 600-volt bypass capacitor 
across the input 6SJ7's screen grid. 
Check the plug and socket of the crys- 
tal pickup; a bad ground here will 
cause noise pickup and hum. Clean 
with a service cleaner and a very fine 
polish; do not use sandpaper or any 
harsh abrasive. Check the hot wire of 
this device for contact. It is made 




Top view of Watch- 
master — watch is 
in holder, recording 
drum in the center. 



MAY, 1956 




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ELECTRONICS 

through a small spring and can give 
considerable trouble, if not perfectly 
clean. 

The amplifier is very sensitive and 
it may be necessary to ground the 
chassis to prevent pickup of high-level 
electrical interference. A small line 
filter may be helpful in eliminating this 
type of trouble. 

The motor and moving parts of this 
instrument are mounted on rubber to 
prevent mechanical vibrations from 
affecting the pickup. If these are defec- 
tive, extra noises will be fed into the 
recorder circuit. See that all the mounts 
are good and the chassis is floating 
freely. 

For a test of machine accuracy it 
should be possible to use a single ear- 
phone and a sensitive shortwave re- 
ceiver tuned to the loudest WWV fre- 
quency. Place the earphone in the 
pickup and advance the gain until the 
1 -second ticks are heard. Now make a 
record and see if the dots are in a 
straight line. As the drum turns five 
times per second, they will not be as 
close as when recording a watch but 
they will give you an accurate test. 
(The standard American watch makes 
18,000 beats per hour — 5 per second. 
This will produce a dot each drum 
revolution.) 

The Watchmaster can be serviced 
with ease by any radio or TV shop, 
using nothing but everyday tools and 
equipment. There is good money in 
this work and it can be had for the 
asking, as the jeweler usually does 
not know that you can repair this kind 
of machinery. Let him know that you 
can repair his pet instrument just as 
well as, and much quicker than, it can 
be done by sending it out of town, and 
you'll have a friend and customer for 
life! Keep 'em ticking! end 

Reference 

Henry O. Maxwell, 44 Modern Watch Rate Re- 
cording,'* Radio-Elbctronics ; August, 1953, 
page 26. 



CORRECTION 

The cuts for Figs. 2-d and 5-b of the 
article "Time Constants . . . What 
they do" on page 37 of the March 
issue are upside down. This causes the 
capacitor charging rates to increase 
rather than decrease with the passing 
of time. 

It was also pointed out that the 
values of the blocking capacitor and 
the resistor in series with the battery 
must be carefully selected. If they are 
not, this network may differentiate the 
incoming square wave and ruin the 
experiment. Too, a discussion of time 
constants is incomplete without mention 
of the R-L time constant. This acts 
exactly like the R-C circuit except that 
it equals L/R in seconds and it affects 
the current through the inductor 
instead of the voltage across the capaci- 
tor. 

We thank Joseph R. Mensch, of Red- 
wood City, Calif., for these corrections 
and comments. 

RADIO-ELECTRONICS 



how long would it take you to solve this service problem? 



- 




SYMPTOM: 

Note the photo: The dial cord obviously 
needs repairing 

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the dial cord without a diagram, but why 
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Folder. It shows the one right way to re- 
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zling over why the dial pointer moves the 
wrong way, why the gang doesn't turn, why 
there's jamming or skipping, You solve 
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minutes with photofact's help. It's just 
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Tu ner and Changer models. And PHOTO- 
FACT is a current service— keeps you 
right up with late model production — 
brings you these exclusive features: 
FULL SCHEMATIC COVERAGE 

1. Famous "Standard Notation" uniform 
symbols are used in every schematic. 
Diagrams are clear, large, easy to read 
and handle. 

2. Wave forms and voltages are shown 
right on the schematic for fast analysis. 

3. Transformer lead color-coding and 
winding resistances appear right on the 
schematic. 

4. Schematics are keyed to parts lists 
and to parts on chassis photos. 



FULL PHOTOGRAPHIC COVERAGE 

5. Exclusive photo coverage of all chassis 
views is provided for each model; all 
parts are numbered and keyed to the 
schematic and parts lists for quicker 
parts identification and location. 

ALIGNMENT INSTRUCTIONS 

6. Complete, detailed alignment data is 
standard and uniformly presented in all 
Folders. Alignment frequencies are 
shown on radio photos adjacent to ad- 
justment number— adjustments are keyed 
to schematic and photos. 

TUBE PLACEMENT CHARTS 

7. Top and bottom views are shown. Top 
view is positioned as seen from back of 
cabinet. Blank pin or locating key on 
each tube is shown. Charts include fuse 
location for quick service reference. 



TUBE FAILURE CHECK CHARTS 

8. Shows common trouble symptoms 
and tubes generally responsible for such 
troubles. Series filament strings are sche- 
matically presented for quick reference. 

COMPLETE PARTS LISTS 

9. Detailed parts list is given for each 
model. Proper replacement parts are 
listed (with installation notes where re- 
quired). All parts are keyed to chassis 
photos and schematics for quick refer- 
ence. 

FIELD SERVICE NOTES 

10. Each Folder includes time-saving tips 
for servicing in the customers home. 
Gives valuable hints for quick access to 
pertinent adjustments, safety glass re- 
moval, special advice covering the spe- 
cific chassis, etc. 




With PHOTOFACT 
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• you service more sets and earn more daily 



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own risk: see your Parts Distributor and buy the 
proper PHOTOFACT Folder Set covering the re- 
ceiver. Then use it on the actual repair. If PHOTO- 
FACT doesn't save you time, doesn't make the job 
easier and more profitable for you, Howard W. 
Sams wants you to return the complete Folder Set 
direct to him and he'll refund your purchase price 
promptly. GET THE PROOF FOR YOURSELF— 
TRY PHOTOFACT NOW! 




Send for Sams' INDEX TO 
PHOTOFACT FOLDERS- 
your guide to virtually any 
receiver model ever to come 
Into your shop; helps you 
locate the proper PHOTO- 
FACT Folder you need to 
solve any service problem 
on any model. You'll want 
this valuable reference 
guide. Send coupon now. 



*These are only a few of the 32 features found exclu- 
sively In PHOTOFACT— the world's finest service data 



HOWARD W. SAMS & to., INC. 



Howard W. Sams A Co., Inc. 

2205 E. 46th St., Indianapolis 5, Ind. 

□ Send FREE Index to PHOTOFACT Folders 

□ I am a Service Technician 



I 
I 

| Name 

| Address. 
1^ City 



..Zone- 



MAY, 1956 



93 



www.americanradiohistorv.com 



RADIO 



SERVICE THE SCHOOLS 



Expanding audio-visual programs 
offer opportunities to the electronic 
technician 




Author makes back- 
stage check of Strom- 
berg-Carlson public 
address system. 



Tape recorders are 
becoming increasing- 
ly popular in educa- 
tion. Pentron CT-1 
right is typical of 
units in use. 





Record players used 
in schools must be 
rugged. Usually, the 
top of case becomes 
detachable speaker 
which can be located 
for better coverage 
than built-in unit. 



By YVON O. JOHNSON* 

HOW would you like to find cus- 
tomers more interested in qual- 
ity work than cheap prices and 
not likely to try to escape pay- 
ing their bills? Certainly you would! 

I am one of those customers. We are 
located in every part of this country. 
Some of my fellow customers are hav- 
ing just as much trouble finding a com- 
petent repair service as you are having 
in finding the perfect customer. 

These prospects are the schools, col- 
leges and universities in your area. If 
you were to visit me in my school, you 
would be pleased at the quantity of 
electronic equipment in use; most of it 
in our audio-visual program. At James 
Lick Junior High School, San Fran- 
cisco, Calif., we use the following elec- 
tronic items for approximately 1,000 
pupils : 

3 16-mm sound motion picture pro- 
jectors 

3 record players with amplifiers 
1 public address system 
3 radio receivers 
1 tape recorder 

I've listed only equipment using elec- 
tronic tubes and have not included 
purely optical items. This equipment 
that I look after and send out for re- 
pairs has about 75 tubes — plus micro- 
phones, connectors, cables and plugs. 
Our schooi is not heavy with electronic 
equipment either. Some schools and 
colleges have TV sets, elaborate paging 
and intercom systems, disc recorders, 
multiple earphone systems for use with 
disc or tape players, and sound-filmstrip 
projectors. 

Let's see what advantages there are 
to you, the technician, in addition to 
just "more business." This type of 
business is equally good for you whether 
you have a large or small shop; shop 
size is important only to the extent 
that you can handle the work within 
a reasonable time limit. I want my 
school's equipment serviced as soon as 
possible, but I hope I'm not as demand- 
ing as the customer who fears missing 
his favorite comedian. 

School systems and colleges are usu- 
ally good pay. You may have to wait 
a little while for your payment while 
the paperwork goes through channels, 
but you don't have the problem of the 
customer moving away. And you'll find 
that I and other audio-visual men will 
not be looking as much for bargains as 



94 



* Audio-visual building coordinator, James Lick 
Junior High School, San Francisco, Calif. 

RADIO-ELECTRONICS 



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MAY, I 956 



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ELECTRICAL 
ENGINEERS 

or 

PHYSICS 
GRADUATES 



nth experience in 
RADAR 



ELECTRONICS 

or those desiring to enter 
these areas... 



The time was never 
more opportune than 
now for becoming 
associated with the field 
of advanced electronics. 
Because of military 
emphasis this is the most 
rapidly growing and 
promising sphere 
of endeavor for the 
young electrical 
engineer or physicist. 

Since 1948 Hughes Research and Develop- 
ment Laboratories have been engaged in an 
expanding program for design, development 
and manufacture of highly complex radar 
fire control systems for fighter and intercep- 
tor aircraft. This requires Hughes technical 
advisors in the field to serve companies and 
military agencies employing the equipment. 

As one of these field engineers you will be- 
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including the most advanced electronic com- 
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RADIO 

do so many home service customers. 

An advantage to you in the long run 
is the indirect advertising you receive 
when servicing schools. School per- 
sonnel cannot help noticing and remem- 
bering that you are maintaining the 
school's equipment. They may then 
think of you when their own and 
friends' radio and TV sets need re- 
pairs. 

Don't overlook the prestige value you 
receive. Should a new customer come 
into your shop to inquire if you know 
how to service tape recorders, think of 
the effect of your being able to mention 
casually, "Oh, yes. We take care of all 
tape recorders belonging to the school 
district." 

How this business differs 

From my professional experience I 
can give you some pointers about the 
differences in this type of work as 
compared to TV servicing in the home. 

Be thorough. You have probably 
found that most TV servicing custom- 
ers are willing to have just the tube 
that is causing the immediate trouble 
replaced if additional repairs for less 
bothersome faults will cost them more 
money. They rightly feel that they 
can call you back whenever the trouble 
becomes worse or when they can afford 
the extra service work. 

Not so with audio-visual equipment! 
Inspect it to locate other defects than 
the main trouble and, if necessary, 
obtain authorization to repair all the 
defects. Preventive maintenance is the 
thought to keep in mind; you will cer- 
tainly please the school if you do. Put 
yourself in my place in the following 
cases to see which one would leave you 
more favorably disposed to the service 
shop. 

Case A : I had sent in a 16-mm sound 
motion picture projector to have a belt 
replaced. Not listed for repair, but 
just as obvious as "no picture" in a 
TV set, was a broken clamp on the cable 
running from the photoelectric cell to 
the audio amplifier. The belt was re- 
placed but the cable clamp wasn't. A 
few days later, the same projector had 
to be sent back for repair of broken 
connections at the end of that cable. 
That time, the clamp was replaced. 

Sure, I had forgotten to list the 
broken clamp the first time, but don't 
you agree that the service shop should 
have replaced it (and charged for it) 
rather than take the chance that re- 
sulted in customer displeasure? 

Case B: I had sent in another 16- 
mm sound projector for belt replace- 
ment. It came back with the belt 
replaced and with missing rubber feet 
on the case put back on. Minor? Yes, 
but wouldn't it show you, as an audio- 
visual coordinator, that the service 
technician had you in mind? 

Your thoroughness is extremely im- 
portant to the school because each re- 
pair job means that the school will be 
losing the use of that equipment for 
several days while the equipment is 
being transported to the audio-visual 




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RADIO 

center, to the service shop, repaired, 
back to the center and finally to the 
school. 

Also, as an audio-visual building co- 
ordinator, I have to produce results in 
the form of equipment ready for use, 
not excuses that the equipment has 
been sent back to the service shop 
again! 

Learn the paperwork. You will prob- 
ably find it necessary to have written 
requisitions authorizing the repair 
work; oral requests to have work per- 
formed are usually backed up by a 
confirming requisition. You may have 
to submit several copies of your bill 
to the school system or college. Once 
you find out how to do these things, 
you should not have any particular 
problem if you observe the rules 
faithfully. In dealing with any 
large organization — business, gov- 
ernmental or school — you lose the 
personal relationship that exists in 
dealing with an individual. The clerks, 
accountants and auditors involved 
in the transaction do not know you. i 
Their only contacts with you are 
through the many pieces of paper they 
see. Their concern cannot be with the 
actual equipment, but only that the 
paperwork has been done according to 
their procedures. However, the direc- 
tor of the audio-visual department for 
the school system will be alert to the 
quality of your servicing. 

Watch for mechanical troubles. In 
servicing for schools you will find a 
higher ratio of mechanical to electri- 
cal troubles than in home servicing, 
because the school equipment receives 
more handling than similar things 
would in the home. A record player 
in the average home is moved little 
and is used by the same few people. 
In schools, a record player might be 
moved among several rooms in one 
day and be used by many people. This 
transportation exposes the equipment 
to mechanical damage. If someone 
doesn't fasten the record player's arm 
each time it is transported, you will 
have a service job. 

Although I spend a good part of my 
time training teachers and students, 
many of them are not as familiar with 
the equipment as they should be. I have 
had cones pushed out of speakers, plugs 
and sockets broken, wires ripped out, 
arms broken off projectors and other 
damage inflicted by intellectual, well- 
intentioned people. 

If you mentally picture two ele- 
phants trying to pull a microphone 
connector apart, you'll have a good 
idea of the handling it will get! 

More audio equipment. In general, 
you'll find relatively more audio than 
radio equipment in school servicing as 
compared to home servicing — public 
address systems, record players, tape 
recorders and motion picture projectors 
with optical and magnetic sound. 

Most of the troubles in the audio 
amplifier section of 16-mm motion 
picture projectors and many obvious 
mechanical breakdowns can be handled 




JERROLD ELECTRONICS CORP. 

2216 Chestnut Street • Philadelphia 3, Pa. 

in Conodo.- Jerrold Electronics (.Canada) Ltd., Toronto 10, On!. 



MAY, 



956 



*7 



www.americanradiohistorv.com 



Superior's New 
Mode/ TC-55 




TUBE TESTER 

The Experimenter or Part-time Serviceman, who has delayed purchasing a higher priced Tube Tester. 
The Professional Serviceman, who needs an extra Tube Tester for outside calls 
The busy TV Service Organization, which needs extra Tube Testers for its field men. 

Speedy, yet efficient operation is accomplished by: 

1. Simplification of all 2. Elimination of old style sockets used for testing obsolete tubes (26, 27, 
switching and controls. 57, 59, etc.) and providing sockets and circuits for efficiently testing 
the new Noval and Sub-Minar types. 

You can't insert a tube in wrong socket 
It is impossible to insert the tube in the wrong socket when 
using the new Model TC-55. Separate sockets are used, 



FOR 



one for each type of tube base. If the tube fits in the 
socket it can be tested. 

Free-point" element switching system 
The Model TC-55 incorporates a newly designed element 
selector switch system which reduces the possibility of 
obsolescence to an absolute minimum. Any pin may be used 
as a filament pin and the voltage applied between that pin 
and any other pin, or even the "top-cap". 
Checks for shorts and leakages between all elements 
The Model TC-55 provides a super sensitive method of 
checking for shorts and leakages up to 5 Megohms between 
any and all of the terminals. Continuity between various 
sections is individually indicated. This is important, es- 



pecially in the case of an element terminating at more than 
one pin. In such cases the element or internal connection 
often completes a circuit. 
Elemental switches are numbered in strict accordance with 
R.M.A. specification. 

One of the most important improvements, we believe, is 
the fact that the 4 position fast-action snap switches are 
all numbered in exact accordance with the standard R.M.A! 
numbering system. Thus, if the element terminating in pin 
No. 7 of a tube is under test, button No. 7 is used for that test. 

The Model TC-55 comes complete with op- 
erating instructions and charts. Housed in 
rugged steel cabinet. Use it on the bench — 
use it for field calls. A streamlined carry- 
tng case, included at no extra charge, 
accommodates the tester and book of in- 
stt uctions. 



'26 



95 

NET 




Superior's new 
Model TV- J I 



TUBE TESTER 



★ Tests all tubes including 4, 5, 6, 7, Octal, Lock-in, Pea- 
nut, Bantam, Hearing Aid, Thyratron Miniatures, Sub- 
miniatures, Novals, Sub-minars, Proximity fuse types, etc. 

★ Uses the new self-cleaning Lever Action Switches for 
individual element testing. Because all elements are 
numbered according to pin-number in the RMA base 
numbering system, the user can instantly identify which 
element is under test. Tubes having tapped filaments 
and tubes with filaments terminating in more than one 
pin are truly tested with the Model TV-11 as any of the 
pins may be placed in the neutral position when 
necessary. 

EXTRA SERVICE — The Model TV-II may be used as an 
extremely sensitive Condenser Leakape Checker. A relaxation 
type oscillator incorporated in this model will detect leakages 
even when the frequency is one per minute. 



it The Model TV-11 does not use any combination type 
sockets. Instead individual sockets are used for each 
type of tube. Thus it is impossible to damage a tube by 
inserting it in the wrong socket. 

★ Free-moving built-in roll chart provides complete data 
for all tubes. 

* Newly designed Line Voltage Control compensates for van 
lation of any Line Voltage between 105 Volts and 130 
Volts. 

it NOISE TEST: Phono-jack on front panel for plugging in 
either phones or external amplifier will detect micro* 
phonic tubes or noise due to faulty elements and loose 
internal connections. 



The model TV-II operates on 1 05- 
130 Volt 60 Cycles A.C. Comes 
housed in a beautiful hand-rubbed 
oak cabinet complete with portable 
cover. 



HI 



50 



NET 




Superior's 
New Model TV- 12 



TRANS-CONDUCTANCE 



TUBE TESTER 



TESTING TUBES 

★ Employs improved TRANS-CONDUCTANCE circuit. An 
in-phase signal is impressed on the input section 
of a tube and the resultant plate current change 
is measured. This provides the most suitable 
method of simulating the manner in which tubes 
actually operate in Radio & TV receivers, ampli- 
fiers and other circuits. Amplification factor, plate 
resistance and cathode emission are all correlated 
in one meter reading. 

* NEW LINE VOLTAGE ADJUSTING SYSTEM. A tapped 
transformer makes it possible to compensate for 
line voltage variations to a tolerance of better than 
2%. 

AiCS\ ri*rvtf> vp*. m - - * SAFETY BUTTON — protects both the tube under test 

ALSU TESTS TRANSISTORS! and , the ' instru ment meter against damage due to 

wrw. overload or other form of improper switching. 



★ NEWLY DESIGNED FIVE POSITION LEVER SWITCH 
ASSEMBLY. Permits application of separate volt- 
ages as required for both plate and grid of tube 
under test, resulting in improved Trans-Conduct* 
ance circuit. 

TESTING TRANSISTORS 

A transistor can be safely and adequately tested only 
under dynamic conditions. The Model TV-12 will test 
all transistors in that approved manner, and quality 
is read directly on a special "transistor only" meter 
scale. 

The Model TV-12 will accommodate all transistors in- 
cluding NPN's. PNP's. Photo and Tetrodes, whether 
made of Germanium or Silicon, 
either point contact or junction con- 
tact types. 

Model TV-12 housed in handsome 
rugged portable cabinet sells for. only 



5 72 



50 

NET 




DOT PATTERN GENERATOR (FOB COLOR TV): 

Although yoci will he ahle to use most of your 
regular stanrtnrtfl • •quipment for tervicinK Color TV, 
the one nrkhtam which Is a -'must" is a Dot Patte ri 
Generator. Hie Dot Pattern pt ejected on any color 
TV Receiver tube by the Model TV-50 will enable 
you to adjust for oroper color cowv-rgence. 



Superior's New 
Model TV-50 



GENOMETER 



A versatile all-inclusive GENERATOR which provides ALL the outputs for servicing: 

A. M. Radio • F. M. Radio • Amplifiers • Black and White TV • Color TV 

7 Signal Generators in One! 



R.F. Signal Generator for A.M. 
v* R.F. Signal Generator for F.M. 
Audio Frequency Generator 



\S Bar Generator 
u 0 Cross Hatch Generator 

Color Dot Pattern Generator 
Marker Generator 



R. F. SIGNAL GENERATOR: The 

Model TV-r»0 Genometer provides 
complete Coverage for A.M. and 
F.M. alignment. Generates Uiidin 
Frequencies from l OO Kilocycles 
to no Megacycles on fundamen- 
tals and from 60 Megacycles to 
180 Megacycles on powerful har- 
monics 



VARIABLE AUDIO FRE- 
QUENCY GENERATOR: In 

addition to a fixed 400 cy- 
cle sine-wave audio, the 
Model TV-."iO Genometer 
provides a variable :iOO 
cycle to 20.000 cycle 
Peaked wave audio signal. 

the 



BAR GENERATOR: The 

Model TV 50 Projects an 
actual Bar Pattern on any 
TV Receiver Screen. Pat- 
tern will consist of 4 to 
1G horizontal hars or 7 to 
20 vertical liars. 



CROSS HATCH GENERATOR: 

The Model TV-50 Genometer will 
project a cross- luttch pattern 
on any TV picture tune. The 
pattern will consist of nnn- 
shiftin?? horizontal nnd vertical 
lines interlaced to provide a 
staple cross-hatch effect. 



MARKER GENERATOR: The Model TV-50 includes all 
most frequently needed marker points. The following mark- 
ers are provided: 189 Kc. . 2H2.5 Kc. . 45fS Kc. 600 Kc. 
1000 Kc. 1400 Kc. 1600 Kc. 2000 Kc. 2500 Kc. 3579 
Kc., 4.5 Mc. 9 Mc. IO. 7 Mc. (3f>79 Kc. is the color burnt 
frequency.! 



THE MODEL TV-50 comes abso- 
lutely complete with shielded leads 
and operating instructions. 
Only „ 



*47 



50 

NET 



EXAMINE BEFORE YOU BUY! 

USE APPROVAL FORM ON NEXT PAGE 



98 



RADIO-ELECTRONICS 



www.americanradiohistorv.com 



Superior's New 
Mode/ TV-60 



20.000 OHMS PER VOLT 




ALLMETER 



FEATURES 

is A sensitive, accurate Volt-Ohm-Milliammeter 
with giant meter and mirrored scale. 

j"" An accurate direct-reading Capacity meter. 

v A Kilovoltmeter. 

An R.F. Signal Tracer. 

v An Audio Signal Tracer. 

v Giant recessed 6V2 Inch 40 Microampere 
meter with mirrored scale assures accuracy 
and easy-reading. All calibrations are printed 
in large easy-to-read type. Fractional divi- 
sions are easily read with the aid of the 
mirrored scale. 



Includes services never before pro- 
vided by an instrument of this type. 

The line cord, used only when making Ca- 
pacity measurements, need be plugged in 
only when using that service. It is out 
of the way, stored in its pliofilm com- 
partment at all other times. 
v* A built-in Isolation Transformer automatic 
cally isolates the Model TV-60 from the 
power line when the capacity service is 
in use. 

Selected, 1% zero temperature coefficient 
metallized resistors are used as multipliers 
assuring unchanging accurate readings on 
all ranges. 

t> Use of the latest type of printed circuit 
guarantees maintenance of top quality 
standard in the production runs of this 
precise instrument. 

A new improved type of high- voltage 
probe is used for the measurement of high 
voltages up to 30,000 Volts. This service will 
be required when servicing color TV receivers. 
Simply plug-in the R.F. probe and convert the 
Model TV-60 into an efficient R.F. SIGNAL 
TRACER permitting the measurement of stage- 
gain and cause of trouble in the R.F. and I.F. 
circuits of A.M., F.M., and TV receivers. 
Plug in the Audio probe and convert the 
Model TV-60 into an efficient AUDIO SIGNAL 
TRACER. Measure the signal levels and com- 
parative efficiency of hearing-aids, public- 
address systems, the amplifier sections of 
Radio & TV receivers, etc. 



Read and compare features and 
specifications below! 

SPECIFICATIONS 

8 D.C. VOLTAGE RANGES: (At a sensitivity of 20,000 
Ohms per Volt) 0 to 15/75/150/300/750/1500/7500/ 
30.000 Volts. 

7 A.C. VOLTAGE RANGES: (At a sensitivity of 5,000 
Ohms per Volt) 0 to 15/75/150/300/750/1500/7500 Volts. 

3 RESISTANCE RANGES : 0 to 2,000/200.000 Ohms. 
0-20 Megohms. 

2 CAPACITY RANGES: .00025 Mfd. to 30 Mfd. 

5 D.C. CURRENT RANGES: : 0-75 Microamperes, 0 to 
7.5/75/750 Milliamperes. 0 to 15 Amperes. 

3 DECIBEL RANGES: — 6 db to + 58 db 
R. F. SIGNAL TRACER SERVICE 

EnaDles following the R.F. signal from the antenna to 
speaker of any radio Or TV receiver and using that signal 
as a basis of measurement to first isolate the faulty stage 
and finally the component or circuit condition causing 
the trouble. 

AUDIO SIGNAL TRACER SERVICE : 

Functions in the same manner as the R.F. Signal Trac- 
ing service specified above except that it Is used for the 
location of cause of trouble In all audio and amplifier 

systems. 



Model TV-60 comes complete 
with book of instructions; pair 
of standard test leads; high* 
voltage probe; detachable line 
cord: R.F. Siflnal Tracer 
Probe and Audio Signal 
Tracer Probe, Pliofilm bag for 
all above accessories is also 
included. Price complete. 
Nothing else to buy. Only 



$52 



50 

NET 



Superior's new 
Model 670- A 




SUPER METER 

A combination VOLT-OHM MILLIAMMETER PLUS 
CAPACITY REACTANCE INDUCTANCE 
AND DECIBEL MEASUREMENTS 



SPECIFICATIONS: 

D.C. VOLTS: 0 to 7.5/15/75/150/750/1,500/7,500 Volt* 
A.C. VOLTS: 0 to 15/30/150/300/1,500/3,000 Volts 
OUTPUT VOLTS: 0 to 15/30/150/300/1,500/3,000 Volts 
D.C. CURRENT: 0 to 1.5/15/150 Ma. 0 to 1.5/15 
Amperes 

RESISTANCE: 0 to 1,000/100,000 Ohms 0 to 10 
Megohms 

CAPACITY: .001 to I Mfd. I to 50 Mfd. (Good-Bad 
scale for checking quality of electrolytic condensers) 

REACTANCE: 50 to 2,500 Ohms, 2,500 Ohms to 2.5 
Megohms 

INDUCTANCE: .15 to 7 Henries 7 to 7,000 Henries 
DECIBELS: —6 to +18, +14 to +38, +34 to +58 



ADDED FEATURE: 

Built-in ISOLATION 
TRANSFORMER reduces 
possibility of burning out 
meter through misuse. 



The Model 670-A comes 
housed in a rugged 
crackle-finished steel cab- 
inet complete with test 
leads and operating in- 
structions. 



$28« 



SHIPPED ON APPROVAL 

NO MONEY WITH ORDER - NO C. 0. D. 



Try any of the instruments on f 
this or on the facing page for 
10 days before you buy. If 
completely satisfied then send 
down payment and pay balance 
as indicated on coupon. No 
Interest or Finance Charges 
Added! If not completely satis- 
fied return unit to us, no ex- 
planation necessary. 

© M. Steir 



MOSS ELECTRONIC DISTRIBUTING CO., INC. 
Dept. D-232, 3849 Tenth Ave., New York 34, N.Y. 

Please send me the units checked. I agree to Day down uayment within 
(0 days and to pay the monthly balance as shown. It is understood 
there will be no finance, interest or any other charges, provided I send 
my monthly payments when due. It is further understood that should 
I fail to make payment when due. the full unpaid balance shall become 
immediately due and payable. 

□ Model TV-60 . Total Price $52.50 □ Model 670-A 

$12.50 within 10 days. Balance $8.00 $7.40 within 10 days 

monthly for 5 months. monthly for 6 months. 



Total Price $26.95 



Total Price $28.40 □ Model TC-55 .... $5 00 



Balance $3.50 



□ Model TV- 1 1 Total Price $47.50 

$11.50 within 10 days. Balance $6.00 
monthly for 6 months. 



□ Model TV-50 Total Price $47.50 

$11.50 within 10 days. Balance $6.00 
monthly for 6 months. 



monthly for 4 months. 

O .Model TV- 12 Total Price $72.50 

$22.50 within 10 days. Balance $10.00 
monthly for 5 months. 



MAY, 1956 



99 



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in ceramics 





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C-D Ceramic Capacitors are made 
from beginning to end under one roof 
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ceramic capacitor production. Every 
process . . . every ingredient is under 
constant control. You can see the 
reasons for C-D's outstanding 
superior quality. 

And to help you, C-D Ceramic 
Capacitors are packaged in compact, 
crystal-clear, easy to handle and always usable 
plastic boxes (no extra charge) . That's why 
Distributors who know carry the complete C-D 
line. See your C-D Distributor today. He's listed 
in your local Classified Telephone Directory. 

There are more C-D capacitors 

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PLANTS IN SOUTH PLA I NF1 ELD. N ■ J. I NEW BEDFORD, WORCESTER AND CAMBRIDGE, 
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FUQUAY SPRINGS, N. C; SUBSIDIARY; THE RADIART CORPORATION, CLEVELAND. O. 



Attention . . . 



Service Technicians' Associations 

Club Members 
Student Groups 

Special subscription rates to Radio-Electronics are available 
to associations, clubs, schools, employe groups, etc. For infor- 
mation write — 

G. Aliquo 
RADIO-ELECTRONICS 

154 West 14 St., New York 11, N.Y. 



100 



RADIO 

easily by a competent radio-TV tech- 
nician. But the optical section, along 
with the optical parts and adjustments 
associated with the sound section, had 
better be left until you are experienced 
in that type of work. However, there is 
nothing so mysterious about it that a 
good service technician could not mas- 
ter with proper study of the optics and 
mechanics involved. 

Do only safe work. I am responsible 
for the safety of my students so I make 
certain that the equipment in my care 
cannot injure a person through elec- 
trical or mechanical hazards. I expect 
any service technician working on this 
equipment to be positive that the ac 
line is not shorting or leaking to a 
metal case, exposed metal parts, the 
microphone or a speaker. 

Think ahead. A Bakelite ac plug may 
be satisfactory in the home but it would 
be hazardous in the school where a 
pupil could step on it, break it and 
then try to insert it in the wall outlet. 
(Don't think they haven't tried it!) 
You have to anticipate unintelligent 
acdon on the part of the user to pro- 
tect him from himself. 

How to get business 

If you are interested in this type of 
servicing, let's take a look at some steps 
Steve Jones, an imaginary service tech- 
nician, took to get this work for his 
shop. Maybe his method can help you. 

He contacted his local school's prin- 
cipal. Steve found out from the prin- 
cipal how the school was supplied with 
audio- visual equipment and how the 
principal went about getting it re- 
paired. Steve was told that there was 
a district audio-visual department to 
which he sent defective equipment and 
was given the name of the audio-visual 
director in charge of that central 
agency. 

He contacted the director. It sur- 
prised Steve when he found that even 
large school systems often do not do 
their own repair work. They may, per- 
haps, employ a man to perform minor 
repairs only. The audio-visual director 
(coordinator, supervisor or whatever he 
may be called) told Steve the policy 
that was followed. Steve stated his 
qualifications and offered the services 
of his shop. He also invited the direc- 
tor to visit his shop to see the test 
equipment and facilities. Steve and the 
director were soon discussing recent 
developments in high fidelity, tape 
recording and film projection. The 
director enjoyed finding someone who 
talked his language ! 

Steve was not able to get the busi- 
ness of repairing 16-mm sound motion 
picture projectors that were under 
guarantee — the director preferred hav- 
ing a factory-authorized service station 
perform that work rather than possibly 
voiding the guarantee. Steve is now 
checking with the manufacturers to 
see if he can qualify and have his 
shop become an authorized service 
station. end 

RADIO-ELECTRONICS 



www.americanradiohistorv.com 



RADIO 

UNUSUAL SERVICING 
EXPERIENCE 

ONE afternoon, a pleasant-appear- 
ing man brought in an expensive 
Philco 116X chassis and speaker. As I 
was quite busy at the time, I jotted down 
the usual complaint, serial and model 
number information on a repair tag 
and gave him his half of it as a receipt. 

The second section of the repair tag 
was the itemized bill that he would 
receive when the work was finished. 
It indicated the parts used, the tubes 
supplied, the labor charges and the 
serial number of the radio. 

A third section was for my record 
file and showed exactly what I had 
done to the radio in question and the 
serial number of the radio. 

The radio in question had two low- 
reading tubes, a shorted screen-bypass 
capacitor and the usual burned voltage- 
dropping resistor. 

I replaced these parts, put in two 
new tubes, checked the alignment of 
the radio and was finished with it. 
Several days later, the customer called 
for the radio, paid and left pleased. 

About three weeks later, he returned, 
the chassis and speaker in his arms. 
He put it on the counter, grinned and 
remarked, "Well, here it is again. I 
hope that that guarantee of yours 
means what you said." 

Tests quickly indicated that the out- 
put transformer was open and further 
testing showed me that the mid-tap 
had opened. As this left no voltage on 
the output tube plates, this meant a 
completely inoperative radio. 

As this was a fairly common fault 
in those days, I had a new universal 
type on hand, and it did not take too 
long to install. I then checked for the 
possible cause. The coupling capacitors 
were OK and grid bias was normal, so 
I supposed that the transformer had 
opened. It was. 

All this time, something seemed to 
be telling me that things were not 
according to Hoyle. Just before I put 
the set on the counter for the customer, 
I went to my record file and took out 
the card that I had filled out on the 
previous repair. I noted the serial 
number on both the second section of 
the tag and the record card. They 
matched on the cards, but they did not 
match the serial number of the radio! 

I slowly counted 10 to keep my temper 
and then said softly, "My friend, some- 
thing is wrong here. This is not the 
radio that I fixed for you 3 weeks ago." 

He colored and then blustered, "Sure 
it is! What are you trying to do? Welsh 
on your guarantee?" 

I laughed grimly and replied, "Not 
a bit. However, I guarantee only what 
I do. This set does not have the serial 
number of the one I repaired. You 
can look yourself . . 

Seeing I was wise, he then replied 
weakly, "Well, you can't blame a guy 
for trying . . ." — W. H. Raring 

MAY, 1956 




CHICAGO STANDARD TRANSFORMER CORPORATION 

3 5 09 ADDISON STREET • CHICAGO 18, ILLINOIS 

Export Sales: Roburn Agencies, Inc., 431 Greenwich Street, New York 1 3, N, Y, ^^^^ 



Say you saw it in 
RADIO-ELECTRONICS 

easyTo learn code 

It is easy to learn or increase speed 
with an Inatructograph Code Teach- 
er. Affords the quickest and most 
practical method yet developed. For 
beginners or advanced students. 
Available tapes from beginner's al- 
phabet to typical mi'ssatfes on all 
subjects. Speed range r> to 40 VVI'M. 
Always ready — no QRM. 

ENDORSED BY THOUSANDS! 

The InstructoRraph Code Teacher 
literally takes the place of an oper- 
ator-instructor and enables anyone to 

ine? a SS i d sta m n : ce ter Th C ^an W d S th o^ successful operators have 
-acquired the code' 1 with the InstructoKraph System. 
Write today for convenient rental and purchaae Plana. 




INSTRUCTOGRAPH COMPANY 



4701 Sheridan RrJ.. Dept. RC. Chicago 40. III. 



Si vous ltsez le frangais 
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Specimen gratuit sur demande 

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QUAM 




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Radio-Electronics is continually alert to maintain a high 
level of integrity in our advertising columns. In the case of tube 
advertising — which has suffered special abuses — we insist that 
all advertisers must warrant that their tubes are: 

New and unused 

Not mechanical or electrical rejects 

Not washed or rebranded 

(See page 57 of the January, 1956, issue) 

We investigate carefully when we have grounds to suspect that 
any advertiser is not living strictly up to these rules. 



new ■ 

ecords 




102 



MONITOR 



Note: Records below are 12-inch LP 
and play back with RlAA curve unless 
otherwise indicated. 

High-Fidelity Test Record 

Written commentary by John M. Conly 

Westminister TRC 

Because high fidelity is so subjective an art 
it is not likely that anyone will ever issue a test 
record that will test everything in a way to suit 
everybody. But this Westminister contribution 
comes closer than any preceding disc I can recall 
and will do a better job in the hands of most 
audiophiles, particularly the less experienced ones 
dependent entirely on listening tests, than any 
other single recording I could recommend. 

John Conly, j n the accompanying brochure, 
does an exceptionally good job of explaining what 
qualities need testing and why. From the exten- 
sive Westminister library the editors have chosen 
well and with discrimination brief selections 
which provide clear demonstrations or tests of 
these qualities. Conly's band-by-band commentary 
explains succinctly what to listen for and there 
is very little reason for any confusion on the part 
of any listener. 

The disc starts with a 440-cycle tone for check- 
ing turntable speed and wow. This is followed 
by a frequency sweep from 15.000 to 30 cycles 
in discreet frequencies and then a continuous 
sweep over the same range. The test tones are 
very clean and free of distortion, particularly 
the very low bass. Finally, there is a 1.000-cycle 
tone in five amplitudes from 0 to —40 db. 

The musical selections demonstrate dynamic 
range, frequency range, transient response, def- 
inition and 10 varieties of tonal and acoustic 
balance. The opening of Dvorak s Symphony No. 5 
is said to demonstrate a range of 60 db from 
softest to loudest passage. The peak is very clean 
and most spectacular played back at concert-hall 
level. There are several passages with a good 
36-cycle bass to shake out rattles. The drums 
from Peter and the Wolf are most awesome, 
though I don't consider them as good a test of 
transient response, stability and hangover as 
those in Westminister's old Scheherezade. Still 
they are a very stringent test, being very for- 
tissimo as well as staccato and are not as likely 
to produce locked grooves. To cap a very good 
job, the music is very interesting and well 
assorted so that there is little likelihood of boring 
anybody. All the selections — about half come 
from the Lais series- — are clean, well defined and 
well recorded. 

GOULD: Fail River Legend 
BERNSTEIN: Facsimile 

Ballet Theatre orchestra conducted by 
Joseph Levinc 

Capitol P-8320 

Two of our brightest contemporary American 
composers get here a very fine recording of re- 
cent ballets. Fall River Legend is based on the 
Lizzie Borden ax-murder case and the music is 
properly frightening in spots. There are some 
very sharp attacks and several big peaks ex- 
cellently recorded. The drum on both sides is 
very fine. Only a moderate degree of triangles 
and tinklers but plenty of sharp brasses. Fac- 
simile, a more subtle and quiet work, is a sort 
of psychological study of frustration. There are 
some fine examples of instrumental leads and 
solos, a pretty big string bass in spots, nice 
highs but not many high highs of any kind. The 
tonal balance of both sides sounded very good 
to me, the liveness is moderate. Those who can 
take modern ballet music should find this good 
listening on a fine hi-fi. 

RADIO-ELECTRONICS 



www.americanradiohistorv.com 



NEW RECORDS (Continued) 
Guitar Music of Latin America 
LuurinHo Almeida, solo guitar 

Capitol P-8321 

You may recall that I liked the previous 
Almeida recording very much as a demonstration 
and test record. This disc, more sophisticated and 
serious, includes Etudes and Preludes by Villa- 
Lobos. two dance-inspired studies by Barroso, a 
prelude and Choro by Barrias, a waltz by Ponce 
and three short pieces by Almeida himself. This 
does not require the virtuosity demanded by the 
classic Spanish guitar music. Nevertheless, if 
you like guitar music at all you'll like this. The 
middle bass is very fine indeed. The presence 
is superb. And there are traces of the finger 
squeaks and fingering and plucking transients, 
etc.. which make such good test material. 

Italy After Dark 

Cyril Stapleton orchestra 

MGM E-3302 

Add this to the small library of popular or 
semipop music suitable for demonstration. Ex- 
ceptionally clean for a pop, it has sharp and 
clean brushed drum high highs and a tfood 
assortment of other percussion instruments. There 
are good pizzicato strings, a mandolin with nice 
transients, an accordion playing with a variety 
of stops. The bass is only fair but the liveness 
and presence are excellent. 

RIMSKY-KOIteAKOV : Scheherazade 
Steinberg conducting Pittsburgh 
Svtnplionv 

Capitol T-8305 

Scheherazade is one of the best of all hi-fi 
show horses and popular with most people as 
music. A, demonstration material this version 
is by no means up to Westminister's WL-5234. 
From a strictly musical point of view I imagine 
it is acceptable. Hut possibly because of the 
excessive liveness of the Mosque in which it was 
played the definition is inferior. Also, neither 
the drums nor the percussion "cutlery" are 
prominent. The drums in the final movement, 
which in the Westminister are like Death knock- 
ing at the door, are here just barely audible. The 
contrast, however, provides a special demonstra- 
tion and test value and 1 for one am happy to 
have both versions. The Capitol version repro- 
duced exactly as recorded sounds the way the 
Westminister would sound on a poor system. So, 
if both versions sound rather similar, there is 
something seriously wrong with the system. 
However, the two can be used together to demon- 
strate the difference between a really fine hi-fi 
system and a poor one — a thing which is some- 
times hard to do if one doesn't have a poor 
system on hand. 

in His Shadow 

Fisk Choir, Dinah Shore, Snooky Lan- 
son, Sylvia Stahlinan, James Mel- 
ton, Joseph MaePherson and Others. 

Dot Records No. 227 

This recording is a memorial dedicated to pre- 
serve the architecturally strange and historic 
Downtown Church of Nashville. It presents the 
entire tramut of religious songs from country 
hymns sung in the Grand Ole Opry Style, through 
spirituals (and a satire of one by Thil Harris), 
Protestant and Catholic hymns sung by popular 
singers like Dinah Shore and Snooky Lanson 
up to AUelluja in the grand opera manner. It 
all sounds excellent. The acoustics of the old 
church are interesting: the voices are fine, 
especially Dinah Shore, Lanson and Morgan. 
The organ bass is especially good behind Dinah 
Shore. The recording technique falls down in a 
spnt or two, but the overall quality is good. Those 
who like religious music, or would like to have 
something in their collection to satisfy listeners 
who do, should like this. 

Proceeds from sales will go to the church. 
Records are available from Vance Memorial 
Music, 154 Fifth Ave., No. Nashville, Tenn., 
for $5. 

DVORAK: String Quartet in G Major 
Barchet Quartet Vox PL-9250 

One way to enhance the presence of a record- 
ing is to brim? into the playback room the 
resonances and acoustical character of the room 
in which the music was played originally. The 
playback room should be "neutral" or dead for 
its own resonances would confound and obscure 
the recorded ones. Here is a rather unique 

MAY, 1956 



MORE 



RANGES 

VISIBILITY 

V.O.M. 



the 



PRECISION 




model 



120 



Gives You What 
You've Ahuays 
Wanted in a 

HIGH-SENSITIVITY 
MULTI-RANGE 
TEST SET 

20.000 OHMS PER VOLT D.C. 
5,000 OHMS PER VOLT A.C, 



I MORE RANGES - 44 of them . . . starting lower and going higher . . . outranging any 
professional V.O.M. of similar size or type. 

♦ AN EXTRA-LOW RESISTANCE RANGE - 2-ohm center scale range, powered by long-lived, 
internal 1.5 volt battery source. 

) AN EXTRA-LOW VOLTAGE RANGE - 1.2 volts full scale, A.C. and D.C. 
^ AN EXTENDED LOW CURRENT RANGE - 60 microampere first D.C. current range. 
^ A LARGER AND EASIER-READING SCALE FACE — extra-large 5V4" meter with full 4*A" 
extra-wide window. 

) SIMPLE, POSITIVE RANGE SELECTION - 18-position, positive-detenting, master range 
selector with low-resistance, dependable, silver-plated contacts. 

) RUGGED, POSITIVE CONTACT JACKS and PLUGS - specially designed, low-resistance, solid 
brass, banana type plugs and jacks. 

Compare these Wide-Spread Ranges and Special Features: 

★ 8 DC VOLTAGE RANGES: 20,000 ohms per v. 0-1.2-3-12-60-300-600-1200-6000 v. 
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record for testing the acoustics of a playback 
room. It is recorded in a "live" studio whose 
reverberation period can actually be measured 
by the decaying echo, especially at the end of 
the first movement The playback room should 
make it possible to hear the difference between 
this and other recordings very plainly and, 
indeed, to measure the echo. Aside from this 
special test value, this is capable of producing 
a high degree of pseudo-stereophonic presence 
which is very impressive and "real." The defini- 
tion of the individual instruments is always 
good. 

GLUCK: Flute Concerto in G Major 

BOCHERINI: Flute Concerto in D Major 

PERGOLESI: Flute Concerto in G Major 
- amillo Wanausek. Flute 
Pro Musica Orchestra of Vienna 

Vox PL-9440 

Another lovely peace offering for the family 
suffering from too much loud demonstration. The 
music is most pleasant, the flute beautifully 
clean and naturally "windy" although rather out 
of scale because so closely miked. No instrument 
makes a lovelier sound on a really fine hi-fi 
system than the flute. 

SCHUBERT: Symphony No. 4 (Tragic), 
Symphony J\o. 8 (tin finished) 
Bamberg Symphony conducted by 
HoIIreiser Vox PL-9370 

DVORAK: New World Symphony 

New Symphony of London conducted 
by Rudolph Schwarz 

Capitol P-8308 
Two of the most popular of all symphonies are 
played with what seems to me adequate compe- 
tence to produce a stunning sound. The Dvorak 
has fine kettledrums and beautiful sharp clean 
strings. The definition is excellent and the solo 
instruments outstanding. Soft passages require 
a low noise and rumble level. The two Schubert 
symphonies have the outstanding Vox bass, the 
Unfinished especially should be most prepossess- 
ing with good speaker systems. 

DE FALL 4: Concerto for Harpsichord 

and Chamber Orchestra 
RIETI: Partita for Harpsichord, Oboe 

Flute and String Quartet 
SURINACH: Tientos 

SyKia Marlowe, Harpsichord and 

Concert 4ris Players 

Capitol P-8309 
A real tidbit for lovers of chamber music. All 
modern music but with a greater variety of mel- 
ody than usual. All are beautifully recorded with 
an awe-inspiring presence. The harpsichord re- 
ceives, for my money, its most accurate and 
felicitous recording. The definition throughout is 
exceedingly good — you can hear the faintest 
harpsichord tinkle even in crescendos and over 
the drums. Not recommended to those who 
haven't learned the special charm of modern 
chamber music, but I'm sure that those who 
have acquired the taste will enjoy it. 

TCHAIKOVSKY: Piano Concerto No. 2 
iano Concerto in F Sharp 

Minor 

Friedrich Wuehrer and Pro Musica 
Orchestra of Vienna Vox PL-9200 
SCHUBERT: Impromptus Op. 90 and 
142 

Ingrid Haehler, pianist Vox PL-8940 
MOZART: Piano Concerto No. 6, Piano 
Concerto No. 8 
Ingrid Haebler and Pro Musica Or- 
chestra of Vienna Vox PL-9290 
Favorite Piano Classics 

Leonard Pennario, Pianist 

Capitol P-8312 

Echoes of Budapest 

George Feyer, Piano and Rhvthni 

Vox VX-850 (10-inch LP) 

Four pianists, four (or possibly five) pianos, 
four styles — high fidelity makes their differences 
obvious to the most unskilled ear. Pennario's 



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NEW RECORDS (Continued) 

piano has a strident, almost barrel-house, treble ; 
Haebler's is sweet and mellow, Feyer's Bharp 
and round and Wuehrer's very resonant. The 
Vox bass is fuller and more resonant than 
Capitol's but any of these will serve as a good 
example of how well today's high fidelity does 
by the piano. 

Many will prefer the standard repertoire 
(Second Hungarian Rhapsody. Prelude in C 
Sharp Major, Clair de Lune, Polonaise in A 
Flat, etc.) on the Pennario record although I 
found his playing very dispirited as if (and I 
don't blame him too much) he were more than 
a little weary of the old warhorses. Wuehrer 
delivers a really old-fashioned bravura, no- 
muscle-spared performance which I imagine 
suits the Tchaikovsky and Scriabin works nicely. 
Personally I liked Haebler's restraint and deli- 
cacy best and I thought her piano sounded best. 
However, I believe most people will find Feyer's 
clever improvisations on various Hungarian 
themes most interesting though, like most pop 
recordings, the bass is a little too heavy and 
the treble by no means as clean as it should 
be. But the piano is good and the music is fun. 

SCHUMANN: Quintet in E flat 
HUMMEL: Quartet in G 
Viator Aller, piano and 
Hollywood String Quartet 

Capitol P-8316 

Charming chamber music in an excellent per- 
formance and recording ; a fine piano, sharp but 
not strident strings. The presence is excellent 
and with just about the right liveness for maxi- 
mum realism in a moderately dead living room. 
Just a touch of overcut distortion in the finale. 
The Schumann quintet was the first coupling 
of the piano with string quartet and is still 
one of the finest; the second movement is one 
of the most moving funeral marches. The 
Hummel quartet is also musically engaging and 
its Mozartian counterpart provides an excellent 
demonstration of definition and the differing 
qualities of the four strings. One of the best 
chamber demonstration records. 

BLOCK, Ernest: Quintet for Piano and 

Strings 

J oh a n a Harris, piano, and 
Walden String Quartet 

MGM E-3239 

This is a quintet of another color entirely. 
Both the piano and the strings get a more 
thorough workout in music in which form and 
rhythm are more important than melody. The 
cello is asked to get down in double-bass range 
and sometimes to pretend it is a pair of 
tympani; the pianist must find portions of this 
sweat-producing work. And while the music is 
delinitely for those capable of the ' domestic 
but good" type of judgment about music, the 
sound is very impressive on a good system and 
provides good measures of definition, IM dis- 
tortion, and even dynamic range. The low range 
of the cello is outstanding for its genuine stringy 
tone, indeed one of the best on records. Excel- 
lent for advanced chamber-music hi-fi fans. 

HARRIS, Roy: Fantasy for Piano and 
Orchestra 

MGM Symphony Orchestra 
conducted hy Izler Solomon 

Abraham Lincoln Walks at Midnight 
Nell Tengeman, soprano, plus piano, 
violin and cello 

MGM E-3210 

Two of Roy Harris' latest works (first played 
in 1954) given a pretty brilliant recording unaer 
the supervision of the composer and presumably 
authentically expressing his ideas. The music is 
strictly for the congoscenti of modern America 
although the Fantasy is thoroughly listenable 
and indeed pleasant, being based on obscure 
American folk motifs. Not hard to take by 
anyone who has the patience to listen to it a 
few times. I found little interest in the cantata 
Abraham Lincoln Walks at Midnight either as 
music or demonstration material. 

END 

Name and address of any manufacturer of 
records mentioned in this column may be ob- 
tained by writing Records, Radio-Electronics, 
1 54 West Ihth St., New York 11, N. Y« 

MAY, 1956 




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106 



Technicians' 

lews 





SELF-LICENSING PLANNED 

The Associated Radio-Television 
Servicemen of New York City and the 
Long Island Radio Guild have added 
themselves to the number of organiza- 
tions who plan to do their own licens- 
ing. The New York City plan proposes 
giving examinations to applicants and 
licensing them as technicians or appren- 
tices. Permits will also be issued to 
shops who employ ARTSNY-licensed 
technicians and who abide by the asso- 
ciation's Code of Ethics. The association 
will guarantee all work done by licensed 
technicians. If a customer does not 
receive satisfactory service, the asso- 
ciation will have the work done by 
another member *and reimburse the 
member. Then a decision will be made 
as to whether action should be taken 
against the first technician. 

The Long Island Guild plan is to 
license shops. Nine requirements must 
be met. These include adherence to the 
Guild Code of Ethics, possession of ade- 
quate test equipment, and employment 
of recognized technicians. 

(Qualifications of techincians are to 
be decided by guild license examiners.) 
The shop must be located in a business 
zone, be open during hours specified on 
the application, have a registered busi- 
ness name and carry adequate liability 
insurance for its customers' and its 
own protection. A 90-day guarantee 
must be issued on all parts installed 
and service done. The license is to be 
displayed prominently in the place of 
business. 

A tentative license fee of $15 per 
shop plus $5 per employe is suggested. 

KING COUNTY ELECTS 

At the March meeting of the King 
County Television Service Association, 
Seattle, Wash., officers elected for the 
coming year were: Bob Kelly, presi- 
dent; Harold Hart, vice president; 
Clayton Faller, secretary-treasurer. 

PROTEST NEDA STATEMENT 

Both Forest Baker, of the new Elec- 
tronic Service Council, and Frank 
Moch, president of NATESA, found 
themselves fully in accord with each 
other in condemning and criticizing 
an editorial in the January NEDA 
Joui-nal. The feature most vigorously 
attacked by both was the statement 
that licensing was usually advocated 
by a handful of service technicians 
whose local reputation w 7 as poor. "If 
this article reflects the opinion of the 
members of the National Electronic 
Distributors Association," stated Baker, 



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TECHNICIANS' NEWS (Continued) 
"it is extremely unfortunate that elec- 
tronics parts distributors are so poorly 
informed about the current situation 
in the TV service industry." He went 
on to point out that the TV service 
industry is in a critical state, and that 
further difficulties might lead to the 
dominance of manufacturer-controlled 
service, a development which would 
most hurt the independent parts dis- 
tributor. 

Moch did not confine himself to this 
point but made it the last of four num- 
bered paragraphs, each of which re- 
futed a statement made in the editorial. 
He objected in turn to the inference 
that there was no record of legitimate 
complaints on the TV user level, that 
elected officials or civic leaders were 
uninterested in licensing and that TV 
service technicians in general were not 
interested in a licensing law nor fully 
able to realize "its harmful conse- 
quences." 

SERVICE GROUPS CONTACTED 

More than 300 letters have been sent 
to radio-TV service associations ask- 
ing their opinions in regard to unity of 
the service industry, according to For- 
est Baker, chairman of the Electronics 
Service Council. This action was taken 
in accordance with decisions made at 
the councils Chicago meeting January 
15 (Radio-Electronics, March 1956, 
page 124). The next meeting is planned 
for Kansas City, possibly for May 18- 
20, Mr. Baker stated. 

DOLLAR CONVERSIONS? 

Speaking before a Senate commis- 
sion, Robert Lee of the Federal Com- 
munications Commission suggested that 
some of TV's allocation problems could 
possibly be solved if it were possible to 
add to the present vhf spectrum some 
channels now controlled by the mili- 
tary. "The conversion problem," said 
Mr. Lee, "would not be as difficult as 
the uhf problem." He went on to say 
that the tuners might be adjusted by 
the individual set owner for "maybe a 
dollar plus a service call." (The opti- 
mistic estimate was apparently based 
on strip type tuners.) 

Mr. Lee made it quite clear that there 
was no immediate probability that new 
vhf channels would be opened to com- 
mercial TV and pointed out that an act 
of Congress would be required to allot 
to the broadcaster frequencies now held 
by the defense forces. 

NEW COLOR SCHOOL IDEA 

More than 175 service technicians 
out of 200 invited came to Dallas to 
hear a plan for a new type of color TV 
course outlined by E. P. Miles of Adleta 
Co., electronic distributors of Dallas. 

The new plan consists of combining 
a correspondence course — in this case 
the nine-lesson course offered by RCA 
Institutes — with in-person review pe- 
riods at the end of each three lessons. 
At least 50 # of the review periods were 
to be devoted to shop techniques — at 
which time the technicians would have 
access to color TV sets to work on. 
(Continued on page 110) 

MAY, ) 956 




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110 



(Continued) 



The course is open to all qualifying 
technicians, whether affiliated with Ad- 
leta or not. Approximately 95% of those 
attending- the meeting passed the quali- 
fying test. In addition to the lessons, 
technicians taking the course were 
offered a color TV set at considerably 
less than key dealer price — the only 
condition being that the technician must 
agree to retain the set for the whole 
term of the course. 

NATESA CONVENTION 

The National Alliance of Television 
& Electronic Service Associations an- 
nounces that the date of the 1956 an- 
nual convention is finalized at Sept. 
14-16. The convention will be held in 
Chicago. A special enlarged edition of 
the association's paper, the XATESA 
Scope, will be published concurrently 
with the convention. The exhibition 
which formed a part of previous con- 
ventions will be omitted to give the 
delegates and visitors more opportunity 
to concentrate on the business meetings 
and technical sessions. 

DEATH THREAT 

Efforts of the Radio and Television 
Association of Santa Clara Valley, 
Calif., to clean up the service industry 
have resulted in what was described as 
a "death threat" over the phone. Presi- 
dent Larry Schmitt told members at a 
recent meeting that he received a phone 
call from a husky-voiced man who said, 
"You're looking for a hole in the head 
if you don't keep your nose out of other 
people's television business." 

Schmitt believed that the threat may 
have come from a crackpot — "probably 
someone whose toes were stepped on in 
association cleanup work." 

In view of the fact that another 
service company was threatened, the 
RTA magazine urged all members who 
receive such calls to call the police, 
crackpot or no crackpot. 

ARTSD LIST> GRIPERS 

An interesting experiment has been 
tried by the Associated Radio-Televi- 
sion Service Dealers of Columbus, Ohio. 
Forms have been given to the mem- 
bers, to be filled in with the names of 
griping and slow-paying customers (in 
two separate lists). These will be con- 
solidated and complete lists of these two 
unpleasant types of fauna distributed 
to the members, so that they can orient 
themselves correctly toward customers 
who fall into the two categories. end 



WHAT A SIGHT 

By Teanne DeGood 
We've learned to service black- 
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To reds and greens and blues. 



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ON REQUEST (see coupon below) 



FREE 



WHAT THE "EDU-KIT" OFFERS YOU 

use of the most modem methods of home training. You will learn radio theory 
construction practice and servicing. meory. 
ci^ U W '" lea , n how . to build rad '°s. using regular schematics; how to wire and 
wJri? r J-f h a f h P rofess ' on al manner; how to service and trouble-shoot rad.os. You will 
Z^lJl th * e i*2 P dar . d ty P e of Punched metal chassis as well as the latest develop- 

ment of Printed Circuit chassis. 

•^. OU o^ vi " J carn the basic Principles Of radio. You will construct, study and work 
wiin RF and AF amplifiers and oscillators, detectors, rectifiers, test equipment You 
will (earn and practice code, using the Progressive Code Oscillator. You will learn 
and practice trouble-shooting, using the Progressive Signal Tracer, the Progressive 
Signal injector, the Progressive Dynamic Radio-Electronics Tester and the accompany- 
ing instructional material. 

You will receive training for the Novice, Technician and General Classes of F.C.C. 
Radio Amateur Licenses. You will build 16 Receiver, Transmitter, Code Oscillator, 
Signal Tracer and Signal Injector circuits, and learn how to operate them. You will 
receive an excellent background for Television. 

Absolutely no previous knowledge of radio or science is required. The "Edu-Kit" 
is the product of many years of teaching and engineering experience. The "Edu-Kit" 
will provide you with a basic education in Electronics and Radio, worth many times 
the complete^ price of $19.95. 

THE KIT FOR EVERYONE 



You do not need the slightest back- 
ground in radio or science. Whether you 
are interested in Radio-Electronics be- 
cause you want an interesting hobby, a 
well-paying business or a job with a 
future, you will find the "Edu-Kit" a 
worth-while investment. 

Here is an excerpt from a letter that 
we received from Loren DePriest. 1496 
4th St., Mansfield. Ohio: "I have spent 
many pleasant hours in constructing the 
radios from the schematics in your 
book, and have learned a great deal 
from them. Being as I am interested in 
Radio, | consider the money spent for 
your course as a wise investment. I 
have learned more from your course by 
actually doing, than I did from an ex- 
pensive course." 

Many thousands of individuals of all 
ages and backgrounds have successfully 
used the "Edu-Kit" in more than 79 
countries of the world. The "Edu-Kit" 
has been carefully designed, step by 
_step, so that you cannot make a mis- 



take. The " Edu-Kit" allows you to 
teach yourself at your own rate. No 
instructor is necessary. 

The "Edu-Kit" is also used for 
courses of study, extra-curricular activ- 
ities, industrial personnel training and 
rehabilitation. The "Edu-Kit" is used 
by Jr. High Schools, High Schools, 
Technical Schools. Jr. Colleges, Col- 
leges, Universities, Industrial firms. 
Rehabilitation Hospitals. Boards of Edu- 
cation, U.S. Govt, agencies. United Na- 
tions Educational, Scientific and Cul- 
tural Organizations (UNESCO), and 
numerous adult, radio and young peo- 
ples' groups and clubs. The "Edu-Kit" 
is also popular with servicemen and 
veterans throughout this country and 
abroad. 

Designed for universal use. the "Edu- 
Kit" operates on any voltage from 105 
to 125 volts. AC and DC. For use in 
countries employing higher line volt- 
ages, a 210-250 Volt AC/DC model is 
available. 



PROGRESSIVE TEACHING METHOD 

The Progressive Radio "Edu-Kit" is the foremost educational radio kit in the 
world, and is universally accepted as the standard in the field of electronics training. 
The "Edu-Kit" uses the modern educational principle of "Learn by Doing." There- 
fore you construct, learn schematics, study theory, practice trouble-shooting — all in a 
closely integrated program designed to provide an easily-learned, thorough and inter- 
esting background in radio. 

You begin by examining the various radio parts of the "Edu-Kit." You then learn 
the function, theory and wiring of these parts. Then you build a simple radio. With 
this first set, you will enjoy listening to regular broadcast stations, learn theory, 
practice testing and trouble-shooting. Then you bui'd a more advanced radio, learn 
more advanced theory and techniques. Gradually, in a progressive manner, and at 
your own rate, you will find yourself constructing more advanced multi-tube radio 
circuits, and doing work like a professional Radio Technician. 



THE "EDU-KIT" 
IS COMPLETE 

You will receive all parts and instruc- 
tions necessary to build 16 different 
radio and electronics circuits, each 
guaranteed to operate. Our Kits contain 
tubes, tube sockets, variable, electro- 
lytic and paper dielectric condensers, 
resistors, tie strips, coils, hardware, 
tubing punched metal chassis. Instruc- 
tion Manuals, etc. 

In addition, you receive Printed Cir- 
cuit materials, including Printed Circuit 
chassis, special tube sockets, hardware 
and instructions. You also receive a 
useful set of tools, a professional elec- 
tric soldering iron, and a self-powered 
Dynamic Radio-Electronics Tester. The 
"Edu-Kit" also includes Code Instruc- 
tions and the Progressive Code Oscilla- 
tor, in addition to F.C.C. -type Questions 
and Answers for Radio Amateur License 
training. You will also receive . lessons 
for servicing with the Progressive Sig- 
nal Tracer and the Progressive Signal 
Injector, a High Fidelity Guide and a 
Quiz Book. 



TROUBLE-SHOOTING 
LESSONS 

You will learn trouble-shooting and 
servicing in a progressive manner. You 
will practice repairs on the sets that 
you construct. You will learn symp- 
toms and causes of troubles in home, 
portable and car radios. You will learn 
how to use the professional Signal 
Tracer, the unique Signal Injector and 
the dynamic Radio-Electronics Tester. 
Wh ile you are learning in this prac- 
tical way. you will be able to do many 
a repair job for your friends and neigh- 
bors, and charge fees which will far ex. 
ceed the price of the "Edu-Kit." Our 
Consultation Service will help you with 
any technical problems you may have. 

J. Stataitis, of 25 Poplar PI.. Water, 
bury, Conn., writes: "I have repaired 
several sets for my friends, and made 
money. The "Edu-Kit" paid for itself. 
I was ready to spend $240 for a Course, 
but I found your ad and sent for your 
Kit." 





FREE EXTRAS 








• SET OF TOOLS 
SOLDERING IRON 
TATION SERVICE 


• RADIO & ELECTRONICS TESTER • ELECTRIC 

• TESTER INSTRUCTION MANUAL • CONSUL- 

• HI-FI GUIDE • QUIZZES • TV BOOK 



30-DAY UNCONDITIONAL MONEY-BACK GUARANTEE 

i MAIL TODAY— ORDER SHIPPED SAME DAY RECEIVED 1 

Order from ad — receive free bonus resistor kit worth $5.00. 

□ Send "Edu-Kit" Postpaid. I enclose full payment of $19.95. 

□ Send "Edu-Kit" C.O.D. I will pay $19.95 plus postage. 

□ Send me FREE additional information descrihinq "Edu-Kit." InCludp FREE 
valuable Hi-Fi, Radio and TV Servicing Literature. 

(Outside U.S.A.— No C.O.D.'s. Send check on U.S. bank or lntern't'l M.0, 
"Edu-Kit" for 105-125 V. AC/DC $20.95; 210-250 V. AC/DC $23.45.) 



Name 

Address.. 



PROGRESSIVE "EDU-KITS" INC. 

497 Union Ave.. Room I I6G, Brooklyn II, N.Y. 



new 

Deiices 





MOBILE TELESCOPIC TOW- 
ER, E-Z Way, travels anywhere 
on trailer. 60 and 85 feet. Oper- 
ated by two men. Tower with 
microwave transmitter attached 
can be up and on the air in less 
than 45 minutes. Orientation 
controls are located at base of 
tower. 

Tower height adjustable by 
winch-cable mechanism. Plate 




at top of each tower for mount- 
ing microwave transmitter that 
can be rotated 360° and tilted 
from 15° below horizontal to 
30° above while standing on 
ground.-- -E-Z Way Towers, Inc., 
Tampa, Fla. 

SELENIUM SUN BATTERY 

converts solar into electrical 
power. Designed as power sup- 
ply for transistorized devices 
such as portable radio receivers 
and transmitters. May be used 
v> ith miniature storage bat- 
teries to supply continuous 
power to load. Supplies elec- 
trical power in milliwatt range 
when exposed to sunlight or 
artificial light. When exposed 
to very bright incident sunlight, 
approximately 10,000 foot can- 
dles, can supply maximum out- 
put power of 5,000,000 watts 




per active square inch at output 
voltage of 0.26 volt per sensi- 
tive element. 

Sun battery illustrated has 15 
photosensitive elements con- 
nected in series. Output voltage 
approximately 4 at maximum 
power transfer, and 8 under 
open-circuit condition. Maxi- 
mum operating temperature of 
battery 85° continuous duty and 
100°C in intermittent use. Un- 
limited life expectancy. — Inter- 
national Rectifier Corp., 1521 E. 
Grand Ave., El Segundo, Calif. 

TUNER - AMPLIFIER, Knight 
Uni-Fi, combines FM-AM tuner, 
magnetic preamp and 10-watt 



hi-fi amplifier on single chassis. 
Housed in cork-grained metal 
cabinet with brushed brass 
panel. Input for record player 
using either crystal or magnet- 
ic cartridge; auxiliary input 
for TV set or tape recorder. 
AM loopstick and FM loop an- 
tennas; 10 tubes plus rectifier 




and germanium diode dettetor. 
Requires H-/xv FM signal for 30- 
db quieting. Amplifier response 
±0.5 db 20-20,000 cvcles.— Al- 
lied Radio Corp., 100 N. West- 
ern Ave., Chicago 80, 111. 

PORTABLE PHONOGRAPH, 

Ballerina, model C-12V. Variable 
speed for control of tempo and 
pitch of 33%-, 45- and 78-rpm 
records. Extended-range 11-inch 
oval speaker and 5-watt inverse 
feedback amplifier. Heat-resis- 
tant ceramic pickup cartridge 




with double-jeweled needle. 
Washable Fabricoid of maroon 
and gray covers case. New- 
comb Audio Products Co., 6824 
Lexington Ave., Hollywood 38, 
Calif. 

PORTABLE HI-FI TAPE RE- 
CORDERS, series 3A Ferro- 
graphs, 3 motors, one a spe- 
cially designed Octaquad syn- 
chronous hysteresis capstan 
motor for long-term speed sta- 
bility, eliminating pitch errors 
on playback. 2 portable models 
of dual-track magnetic recorder 
in 3% and 7% ips, 7% and 15 
ips, respectively. Both accom- 
modate 1,750-foot reels of 
standard tape, have one-knob 
selector control, auto-stop 




112 



RADIO-ELECTRONICS 



www.americanradiohistorv.com 




Gm. & Em. ULTRAFAST 

TUBE & TRANSISTOR TESTER 



PRECISE MODEL 116K in kit form. . 
PRECISE MODEL 116W factory wired 



Servicemen know the Precise Model 1 1 1 (the winner in an independent survey) 
easily rates "the finest tube tester in the field" at any price, BUT FOR AN ON 
THE JOB QUICK-TEST ... the fastest, most accurate is the PRECISE Model 116. 
What's more you test tubes the foolproof method inherent in the famous Precise 
Model 111. 

Did you ever wish you could plug in 5 of the same type tubes at once and check 
each one individually by rotating a switch? YOU CAN WITH THE PRECISE 
MODEL 116— Plug in 5 IF tubes and let them heat up at once and then check 
each one separately by rotating the TUBE BANK switch. ACTUALLY CHECK 5 
TUBES IN 20 SECONDS, 4 SECONDS PER TUBE. 

The Precise Model 111 taught the lesson that IF amplifier tubes (like the 6BC5 
or 6AU6) should be tested for Gm (mutual transconductance) while the power 
amplifiers (like the 6L6) should be tested for Em (emission)— that's ULTRAFAST 
Model 1 16 test! It checks each section of each tube separately ... by rotating the 
FUNCTION SWITCH . . . each triode of a dual triode is checked individually . . . 
each diode and the triode of a duo-diode-triode is separately tested and not 
lumped as in other testers . . . and a pentode is tested as a pentode— not a diode. 
TRANSISTORS, SHORTS, GAS, LIFE, Em, Gm etcetera can be tested with the 
PRECISE Model 116. 

You can inexpensively extend the Precise Model 116 to test filament current, etc. 
The Model 116 gives an accurate, ultra-fast (3 basic knobs for testing) check of 
television tubes! 

No Surplus— An etched panel— beautiful Moleskin covered wood carrying case 
and cover and specially simplified instructions makes the PRECISE MODEL 116 
THE FINEST FAST-CHECK TUBE TESTER AND DOLLAR EARNING TRAVELING 
COMPANION A TV SERVICEMAN EVER HAD. 

Not yet at your distributor. Order NOW to insure early delivery. 

SEE YOUR LOCAL DISTRIBUTOR FOR PROOF OF WHAT WE OFFER - OR WRITE 
US FOR DOCUMENTARY RESULTS OF AN INDEPENDENT SCIENTIFIC SURVEY. 




THE FAMOUS MODEL #111 

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lUW $139.95 

Inel. Carrying Case & Cover 



THE FIRST LOW PRICED 
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300K $99.95 

300W $199.50 





LOW PRICED 5" SCOPE 

315K - $49.95 

31 5W $84.95 



THE FIRST AND ONLY 
8V2" COLOR SCOPE 

308K $129.50 

308W $229.50 




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9071 K $35.95 

9071W $49.95 

WRITE FOR CATALOG RE 5-6 






LOWEST PRICED 
WIRED 4Vfe" VTVM 

909K $25.98 

909W $37.50 



RF-AF-3AR GENERATOR 
with pre-assembled* head 

630K . $33.95 

630KA* $38.95 

630W $53.95 



LOW PRICED RF SIGNAL GENERATOR 
"BEST BUY" IN GEN. FIELD 

610K $23.95 

610KA pre-assembled head $28.95 

610W $39.95 



UNIV. AF, SINE, SQ, & PULSE GEN. 

635K $33.50 

635W $52.50 



Prices slightly higher in the West. Prices and 
specifications subject to change without notice. 



PTAK $2.95 
PTAW $4.25 



SEE THE MANY MORE PRECISE INSTRUMENTS AND PROBES AT YOUR DISTRIBUTOR TODAY! 



precise 



DEVELOPMENT CORP. oceanside, new york, u.s.a. 



www.americanradiohistorv.com 



NEW DEVICES 

switch, 60-second rewind, sepa- 
rate bass and treble controls 
and output for 15-ohm exten- 
sion speaker. 

Frequency response within 
±2 db between 50 and 10,000 
cycles at 7% ips, 40 and 15,000 
cycles at 15 ips. Signal-to-noise 
ratio better than 50 db between 
200 and 12,000 cycles. Output 
stage provides 2% watts of low- 
distortion power into 15-ohm 
self-contained elliptical speaker. 
18 x 17^ x 9% inches. 50 
pounds. — British Ferrograph 
Recorder Co., Ltd., London, 
England, available through 
Ercona Corp., (Electronic Div.), 
551 Fifth Ave., New York 17, 
N.Y. 

HI-FI CABINETS, 10 units, 9 
cabinets and 1 base in ST series. 
Modular and identical in width. 
16-, 21- and 32-inch heights. 16- 
inch depth permits all-purpose 



CORNER FOLDED-HORN EN- 
CLOSURE and 4-way loudspeak- 
er systems, Centurion, feature 
of E- V Georgian on smaller 
scale. Single - path indirect- 
radiator folded horn uses walls 
corner to extend bass reproduc- 
tion helow 35 cycles, improve 
transient response, lower dis- 
tortion. Integrates with matched 
speaker system as 4-way repro- 






storage. Cabinet doors and 
moldings of birch. Cabinet 
shells constructed of heavy, 
%-inch white pine plywood. — 
— Cahinart, 99 North 11th St., 
Brooklyn 11, N.Y. 



ducer. 42 x 29 x 22V2 inches. 
Factory-assembled 4-way speak- 
er system or do-it-yourself kits, 
enclosure kit, 4-way package of 
driver components. — Electro- 
Voice, Inc., Buchanan, Mich, 

PREAMPLIFIER- EQUALIZER, 

Model TR-1, all transistor type. 
Hum level zero with no micro- 
phonism. Microphone selector 
allows use as phonograph or 
microphone preamp. .033-watt 
drawn from self-contained bat- 
tery. 3 transistors; printed wir- 
ing throughout. Use with any 
amplifier, audio control or sound 
system. RIAA equalization. 3 
controls on panel for flexibility 
of function. Cartridge imped- 
ance selector permits use of 
TR-1 with magnetic cartridges, 
including low-level types; does 
not require transformer. Vol- 



ume control to be direct-con- 
nected to basic amplifier which 
has no level control. 12 ounces. 
Self-contained; fully shielded. 
—Fisher Radio Corp., 21-21 44th 
Dr., Long Island i ity 1, N. Y.. 

CUSTOM-BUILT HI-FI SYS- 
TEM flexible in size and layout. 
Adaptable to almost any de- 
mand. Consists of Gray viscous- 
damped tone arm, turntable, 
amplifier, preamp and speaker. 
Can be adapted for use in 
hotels, restaurants, schools, 
churches, concert halls, homes, 
etc. Gray Research & Develop- 
ment Co., Inc., 685 Hilliard St., 
Manchester, Conn. 

SUBIV1INIATURE PM SPEAK- 
ER, for transistorized circuitry, 
JV2 inch in diameter and 15/16 



(Continued) 

inch deep. Alnico 5 magnet; 
voice-coil impedance 10 ohms. 
Weighs 1% ounces. Mounting 
centers 1 9/32 x 1 9/32 inches. 
—Lafayette Radio, 100 Sixth 
Ave., New York 13, N.Y. 

HI-FI MANUAL RECORD 
PLAYER, Starlight. Variable- 
speed motor drives precision- 
machined 12-inch aluminum 
turntable with center-drive 
action. Built-in illuminated 
stroboscope permits speed ad- 
justment to perfect pitch over 




range of 16%-85 rpm. Vernier 
tvpe speed control. Wow and 
flutter held to 0.2 volt and 
rumble more than 40 db below 
average recording level. 

Pickup arm has double-wrist- 
action arm movement; simple 
change of cartridges or clean- 
ing. Ball bearing swivel mount. 
Turntable and pickup arm 
mounted on natural birch base. 
Overall base dimensions 16 x 
17% x 6% inches. — Melzner 
Engineering Corp., 1041 North 
Sycamore Ave., Hollvwood 38, 
Calif. 

MASTER TV CHANNEL CON- 
VERTER, model MVC, high- to 
low-channel vhf converter. Oper- 



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ELIMINATES NOISE due to dirt dust and corrosion 
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JUST SPRAY ON . , . convenient power apray can 
does the job in a wink. No need to dismantle 
chassis. 

CLEANS AND LUBRICATES contacts, controls, re- 
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SAVES TIME AND MONEY — gets the job done fast 
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SEE US 



What articles would you like 
to see published in RADIO- 
ELECTRONICS? 

Maybe you're the man to 
write them. 

Ask for an author's Guide. 

Radio-Electronics 
154 West 14th St. 
New York 11, N.Y. 



114 



RADIO-ELECTRONICS 



www.americanradiohistorv.com 



Millions 

are enjoying 

Better TV with 




NEW COLORS! 
Forest Green 
and Ivory 

Beautiful new decorator models U-98 and 
T-12 now available in both Forest Green 
and Ivory colors, as well as the standard, 
rich mahogany grain! 





Model U-98 — The first and finest fully 
automatic rotator — "just set it and forget 
it!" No swinging or drifting — points instantly 
to target station. Has 32 distinct improvements. 
The best rotator for all stations, all channels, 
yHp f uhF and Color! Available in 3 beauti- 
ful shades List Price $39.95 




Model T-12 — With exclusive Tenna-Teller 
pointer. Gives constant direction readings, 
wholly accurate, dependable. Striking de- 
sign with finger-tip rocker control bar on top. 
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Model K-22 — Lowest-priced quality 
rotator on the market. Has finger-tip control. 

Available in standard color only 

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EXPANDS THE NATION'S TV AUDIENCE! 

In more than two million homes, from coast to coast, viewers get 
better TV . . . thanks to Alliance. And in fringe areas, Alliance 
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no television! Turning the antenna . . . makes for clearer, 
interference free reception. Alliance Tenna-Rotor increases the 
effective signal range of stations everywhere! 

USES TV TO TELL ITS OWN STORY! 

For 7 years Alliance TV spots have run consistently to demonstrate 
and sell. By using television as its principal medium, Alliance has 
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... has always been the largest national TV accessory advertiser. 

AND WHEN COLOR TV COMES . . . 

Color TV is highly critical, more sensitive to reflections. For full 
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GARAGE DOOR 

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OPERATOR 



dash) automatic garage 
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tion. Customers gleamwhen 
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ihe ALLIANCE MFG. CO., inc. 

ALLIANCE, OHIO 



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115 



www.americanradiohistorv.com 



A GOOD TUBE TESTER 

EMC Model 209 




"... Serviceman's 

BEST FRIEND 



r>r> 



"When I'm trying to analyze and correct a circuit TOUGHIE...ifs 
a great feeling to reach for my EMC Model 209 Emission-Type Tube 
Tester and know Til get fast, absolutely accurate checks for quality, 
shorts, leakage, continuity, and opens on all modern and future 
tubes . . . that new, modern, 3y 2 " plastic meter makes quick servic- 
ing easy. You'll like this professional, multi-function instrument 
because it also rejuvenates picture tubes when used with Model 
CRA Picture Tube Adaptor ... a unique flexible switching system 
assures that you can test all future types too! Best of all, this 
precision instrument is priced low 

its handy size (63/ 4 " x Vj{ 
x 4") makes it ideal for 
home calls." 




^Complete with plastic-covered, 
detailed instruction book and tube listings. 

Yes, send me full technical information about Model 209 and a 
complete catalog of other EMC Instruments re-s 
name 



OCCUPATION. 

COMPANY 

STREET 



CITY_ 



-STATL. 




ELECTRONIC MEASUREMENTS CORP. 
280 LAFAYETTE STREET 




NEW DEVICES 

ates at antenna site for com- 
munity installations to reduce 
signal loss in long transmission 
lines. 33-db gain with low-noise 
grounded-grid amplifier. 1-volt 




rms output at either 75-ohm 
outlet. Third 75-ohm fitting for 
input from high-channel Yagi. 

All-channel vhf mixing net- 
work for other MVC converters 
or MCS channel amplifiers in 
system. Fused power supply and 
ac receptacle for power plug of 
next unit. Enclosable in model 
MRH-A weather and radiation- 
proof housing.— Blonder-Tongue 
Labs., Inc., 526-36 North Ave., 
Westfield, N.J. 

REPLACEMENT TRANSFORM- 
ERS for flybacks used in most 




types of modern TV receivers. 
— Raypar, Inc., 7800 W. Addison 
St., Chicago, 111. 

COLOR TV OSCILLOSCOPE, 

model 001, full 5-mc bandwidth 
for color TV servicing. Dc posi- 
tioning prevents bounce or 
overshoot. Push-pull vertical 
amplifier sensitivity .02 volt per 
inch. Retrace blanking ampli- 




fier. 2-step compensated attenu- 
ator input. Positive or negative 
synchronization of input volt- 
age or from external source. 
Built-in 60-cycle phasing con- 
trol and blanking amplifier for 
TV servicing. Astigmatism con- 
trol. — Electronic Measurements 
Corp., 280 Lafayette St., New 
York, N. Y. 

SIGNAL-TRACER PROBE, 

wodel 262, permits checking ac 
waveform voltages in horizon- 
tal and vertical oscillator cir- 
cuits, drive voltage to horizon- 
tal output tube, sweep-circuit 
output, local -oscillator opera- 




tion, sync-circuit signals, if 
output, audio signal, etc. Per- 
mits top-chassis checking of 



( Continued) 

many ac waveform voltages in 
TV receiver. Plugs into any 
20,000 ohms-per-volt VOM.—Fu- 
turamic Co., 2500 W. 23 St., 
Chicago, 111. 

LONG-SHANK ADAPTER for 

TrolMaster, the tool for clean- 
ing and lubricating TV and 
radio controls without remov- 
ing chassis from set or taking 
back off cabinet. With 7-inch 
adapter which screws on, Trol- 



Master can be used on controls 
with shafts up to 7 inches long. 
Made of solid brass, will not 
corrode when used with any 
chemical normally used in elec- 
tronics industry.— R-Columbia 
Products Co., Inc., 305 Wauke- 
gan Ave., Highwood, 111. 

ELECTRONIC DIAGRAMMER. 

No drawing experience for pro- 
fessional-looking circuitry plans 
by running pencil, pen, or 




stylus through any combination 
of engraved electronics symbols. 
Rigid transparent Vinyl tem- 
plate includes commonly used 
electronics symbols; beveled for 
ease and accuracy. 4.25 x 6 5 x 
.040 inch. Symbols include usu- 
ally tedious-to-draw pronged 
tube bases, cathode-ray tubes, 
resistors, elements and coils. — 
A. Lawrence Karp, 16 Putnam 
Park, Greenwich, Conn. 

PAPER TUBULAR, Comet, 
molded-plastic metallized paper 
capacitor. Miniature, self-heal- 
ing, lightweight, heat-resistant, 
moisture-safe, plastic shell. 
Bonded end-seal eliminates en- 

I — i\ ^Si 

s rj^Sr 

vironmental effects. Reliable 
operation from — 65V to 
+ 125°C. Leads won't pull or 
melt out. — Astron Corp., 255 
Grant Ave., E. Newark, N.J. 

COUNTER STAND for Buna- 
Quick model 500 portable tube 
checker (page 52, March 1956, 
issue). Four rubber feet. Rail 
holds instrument cover in ver- 




116 



RADIO-ELECTRONICS 



www.americanradiohistorv.com 



NEW DEVICES 

tical position. Weighs 6 pounds; 
7 x 15*6 x 14*4 inches.— B & K 
Manufacturing Co., 3726 N. 
Southport Ave., Chicago 13, 111. 

RACK AND PANEL TYPE 
CONNECTORS, DPE, made up 
of 40 contacts. Narrow for 
crowded installations. Die-cast 
aluminum shell (3 15/16 inches) 
protects insert and contacts. 
Positive polarization by key- 
stone design, construction fea- 
ture of many connectors in 
smaller rack and panel series. 
Flashover rated at 1,700 volts, 
60 cycles, ac rms at sea level. 
Mated connector 0.381 pound. — 
Cannon Electric Co., 3209 Hum- 
boldt St., Los Angeles 31, Calif. 

E\ CUMULATED RESISTORS, 

CE 100, CE 200 series and PW 
types, feature several improve- 
ments, including reduction of 
thermal hot spots through 
greater conductivity, increased 
tensile strength, resulting in 
greater mechanical strength 
when operating at higher ambi- 



ent temperatures and 15% 
greater wattage dissipation 
through improved surface emis- 
sivity. Where accurate resis- 
tance is a requisite, Cinema- 
Alloy E resistance wire is used. 
Housing of black epoxy with 
circle of yellow epoxy at each 
end of resistor. — -Cinema Engi- 
neering Div., Aorovox Corp., 
Burhank, Calif. 

SELENIUM TV RECTIFIER, 

AirKore. Open-paced 6-contact 
spring for large contact area 
and uniform temperature rise 
across surface of rectifier plate. 
Optimum air circulation around 
plates, through core and spring. 
Maximum air flow in vertical 
mounting positions. In all 
standard sizes, stud and eyelet 
construction - -International 
Recti Her Corp., El Segundo, 
Calif. 

PRECISION POTENTIOM- 
ETER, Vari-Phase. single-turn 
type with simplified phasing. 
Permits external independent 
phasing of each sectional cup 
without affecting phase rela- 
tionships of others in group. 
Phasing may be applied after 
mounting in equipment to cor- 
rect or cancel any mechanical 
or electrical errors that devel- 
oped during or after assembly. 
Done by loosening clamping 
nut, moving terminal board in 



desired direction, then retignt- 
ening. No clamping rings to 
hold cups. Available in 5 dif- 
ferent sizes: %-, 1 1/16-, 1%-, 
2 and 3-inch diameters. — (Jiar- 
ostat Mfg. Co., Inc., Dover, N. H. 

SUBMIMATURE CAPACI- 
TORS, type NT tantalum polar- 
ized electrolytic. Ratings from 



( Continued) 

0.5-16 volts dc: capacitances 
from .08-30 //f; case sizes 3/32 
or % inch in diameter and 
6/32-V2 inch long. For tran- 
sistor circuits in hearing aids 
and miniature radio receivers, 
printed-circuit assemblies, sub- 




miniature controls and other 
very small low-voltage devices 
designed for —20 to 55 n C oper- 
ation. — Cornell Dubilier Elec- 
tric Corp., So. Plainfield, N. J. 

MINIATURE GLASS TRIM- 
MERS, models VC 9G and JOG. 
VC 9G's capacitance range 0.5 
to 8.5 H^f; temperature range 
-55 c to +125 C C; dielectric 
strength 1,000 volts dc; Q at 1 
me greater than 1.000; insula- 



tion resistance greater than 
2,000,000 megohms. VC 10G is 
the same as VC 9G except 
slightly smaller and has a capac- 
itance range of 1 to 4 5 H^f . 
JFD Electronics Corp., 1462 
62 St., Brooklyn, N.Y. 

MINIATURE SELENIUM REC- 
TIFIER, half- wave stack types 
8Y1B and 8J1B. Terminals snap 
into printed-wiring board. Rated 




at 30 ma and 65 ma at oif-line 
voltages with capacitive load 
in 45 C C ambient temperature. 
Mount in 3/32-inch diameter 
holes spaced on 27/64-inch cen- 
ters.— Radio Receptor Co.. Inc., 
Semi-conductor Div.. 251 W. 
19th St., New York 11. N.Y. 

PLUG-IN ADAPTER, for Wes- 
ton model 749 miniature ac 
clamp volt-ammeter. Plug re- 
ceptacles on either side one 
reduces scale range of model 
749 by factor of 10, permitting 
low current measurements; 




other for reading ampere scale 
directly. Adapter plugs into 
ac line, appliance connects to 
adapter and clamping jaws of 
instrument inserted through 
adapter opening. — Weston Elec- 
trical Instruments Corp., 614 
Frelinghuysen Ave., Newark 5, 
N. J. END 



All specifications given on these pages ore from manufacturers' data. 
MAY, 1956 



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VOM 
PROBES 




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Type 261 V-O-M High-Ohms Probe. 
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Type 262 V-O-M Signal Tracer Probe. 
Now you can read signal voltages with 
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V-O-M. Solve tough sweep circuit 
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oscillators ... all without removing the 
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Chicago 8, Illinois 
Representative Inquiries Invited 

118 



\ [ 


r 

rubes 

Transistors 

h— 







2NI75 

A new hermetically sealed, germa- 
nium-alloy junction transistor, the 
2N175, has been announced by RCA. 
The p-n-p type is designed especially 
for use in the preamplifier or input 
stages of transistorized audio equip- 
ment operating fronr] extremely small 
input signals. 

Because of its exceptionally low noise 
factor of 6 db maximum and its freedom 
from microphonics and hum, the 2N175 
can be operated from low- impedance 
low-level devices such as magnetic 
microphones and magnetic pickups 
without an input coupling transformer. 

In a common-emitter type circuit, 
the 2N175 features an exceptionally 
low wide-band noise factor, a current 
amplification ratio of 65 and a matched- 
impedance power gain of approximate- 
ly 43 db. The transistor is 0.026 inch 
in diameter, 0.495 inch in seated length. 

Maximum ratings for class-A audio- 
frequency service are : collector voltage, 

10; collector current, —2 ma; collec- 
tor dissipation, 20 mw; emitter voltage, 
10 ; emitter current, 2 ma ; ambient 
operating temperature, 50 °C. 

SILICON POWER RECTIFIERS 

Developed by CBS-Hytron, the 1N503 
through 1N526 feature exceptionally 
large power-handling capacity for their 
size. These silicon power rectifiers 
operate with extremely high reverse 
voltages and low reverse currents. This 
feature, together with a very low for- 
ward voltage drop, enables the rectifier 
to deliver large power to the load with 
relatively little dissipation. Because 
of their low thermal resistance the 
rectifiers operate in ambient tempera- 
tures up to 125°C. 

The units are available in three 
shapes (see photo), depending on the 
heat dissipation required. The smallest 
unit can handle % ampere without an 
additional heat radiator and features 
pigtail construction, particularly suited 





HER0U9K 

PAPER TUBULAR 
CAPACITORS 





application 

J ) OURAMlC 

W&S) I I MFO, V. O.C.W. I 




capacity 

and 

climate 

Available at ANY Aerovox Dis- 
tributor at ANY time for your 
convenience. 




DISTRIBUTOR SALES DIVISION 
NEW BEDFORD, MASS. 



in Canada: AEROVOX CANADA, LTD., Hamilton, Ont. 
Export: Ad Aunemo , 89 Broad St., New York, N. t, 
Cable Auriema, N. Y. 



RADIO-ELECTRONICS 



www.americanradiohistorv.com 




Some l!4-inch piece of Perma-Tube 
can be used for telescoping masts or 
with another 114 -inch piece to make 
smaller 2-piece masts. 



50 





2i± 



Why buy assembled telescoping masts? 
Use J&L Perma-Tube in 10-foot lengths 
and easily make your own 

Get flexibility in your stock 

SAVE MONEY-SAVE SPACE 



Only J&L Perma-Tube offers: 

• Joint design which provides instant 
field assembly. 

• Machine-fitted joints that insure close 
tolerance for high strength and rigidity. 

• Guy wire ring position that eliminates 
all binding and guy wire interference. 

You can now "tailor-make" your own 
TV masts up to 50 feet high by using 
standard 10-foot lengths of 16-gage 
Perma-Tube — and save money. Five 
diameters are available in easily-handled 
cartons from your local distributor. 
Largest base section OD is 2Va inches 
and each telescoping section is Vi-inch 
smaller, the smallest section having an 
OD of 1 Va inches. 



Buy only a carton each of five different sizes of 
Perma-Tube {\ l A to 2^-inch) and make any tele- 
scoping TV mast up to 50 feet in height. Hardware 
— cotter keys or bolts, clamps and guy rings— may 
also be secured from your distributor. 



Corrosion-resistant Perma-Tube is 
treated with Vinsynite — then coated 
both inside and outside with a metallic 
vinyl resin base. It's made of a special, 
high-strength, J&L steel tubing. A 10- 
foot section of Wa inch diameter by 
16 gage is capable of supporting a 
weight at its center point of 200 pounds 
with a minimum of deflection and 
permanent set. 



J&L Perma-Tube— best for strength and rust protection 



Jones & Laughlin ^TTT 

STEEL CORPORATION • PITTSBURGH 9IEEIl 



MAY, 1956 



119 



www.americanradiohistorv.com 



Ask "The Man on the Roof" why he prefers 





How valuable is a Serviceman's time? 5$ a minute? 
. . .7$ a minute? . . . lot a minute? 



South 





River's New Ratchet Type Chimney 
Mount Saves 10 Minutes 
Per Installation! 



It's the fattest, simplest, most convenient 
ever manufactured! 

Mounting Is factory assembled with band at- 
tached. No assembly of eyebolts, banding, band- 
ing clips, nuts, etc., Is necessary for chimney 
mounting. 

South River's New Ratchet Type 
Chimney Mount is 8 WAYS BETTER: 

1. Heavy gauge steel construction. 

2. Banding naturally unwinds for easy mounting. 
No troublesome watchsprlng effect! 

3. Embossed and welded for extra rigidity 
and strength! 

4. Ratchet of aircraft type aluminum, forged 
and heat-treated for maximum toughness and 
strength. 

5. Fine ratchet teeth insure positive tightening 
of banding. 

6. Banding is factory assembled to mounting. 

7. Zinc plated, golden iridite finish. 

8. Available with galvanized banding (Model RT) 
or stainless steel banding (Model RT-ST). 



1. Encircle chimney with 
banding and thread 
through slotted shaft. 




g. Tighten banding with 
wrench. 



RATCHET 
GUY WIRE 
TIGHTENER 

Eliminates turn- 
buckles! Fastens to 
! wall or roof with 
screws. Extra space 
between tightening shaft and base per- 
mits large tightening capacity. Same- 
sturdy construction as ratchet chim- 
ney mount. 




HIGH STRENGTH 
ALUMINUM GUY 
CABLE, HIGHLY 
CORROSION 
RESISTANT 
Special 56S Alclad 
alloy. 7 strands, 17 
gauge specially tempered and normal- 
ized. Special tight weave. Will not 
rust or stain. Specifically for guying 
use. Breaking strength: approx. 500 
lbs. pull. Boxed in 100 ft. coils or 
ten 100 ft. coils, interconnected, 1000 
ft. to box. 



PI0NHR MANUFACTURER AND OUTSTANDING PRODUCER OF THE FINEST LINE OF ANTENNA MOUNTING ACCESSORIES 



WRITE FOR OUR NEW 1956 CATALOG 



The June RADIO-ELECTRONICS 
Goes on sale May 24 



ELECTRONICS 



ENGINEERING DEGREE 




Prepare for un- 
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tun ties or ,he IN 27 MONTHS 

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Earn >our U.S. degree in 27 months at Indiana Technical 
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MONTHS in Aeronautical. Chemical. Civil. Electrical 
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Please send me free information on B.S. ENGINEERING 
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Name 



SPECIAL "HI-FI" OFFER 

Amazing woven saran Hi-FI Fabrics now avail- 
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In Mahogany, Walnut, or Ulond at the special 
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HI-FI FABRICS INST.. P.O. Box A, Huntiniton Station, N. Y. 



LA BOX CHASSIS 
LMB OFFERS FREE 

inside LMB boxes 

10 tested kit diagram Projects for the builder. Each 
one of these kit diagrams Mi ill by a recognized expert. 
Kit projects are complete in every detail. Circuit dta- 
uraxn. Photo of project l.oth front and rear photo. Rear 
plicto shows wirlnt? and parts. Detailed instructions 
for buildinsr, complete Parts list and approximate cost. 
Complete to build except parts and your distributor 
can supply the Parts. Ask your distributor for the list 
of LMB kit Diagram Projects. If he does not have 
them, write to 

Lkk D 1011 Venice Blvd. 
Afl D Los Angeles 15. Calif. 



NEW TUBES AND TRANSISTORS (Continued) 

for printed circuits. The second unit 
has a screw type mounting and can 
carry 1 ampere. The third has a hex- 
agon base screwstud mounting and is 
capable of handling l 1 ^ amperes. 

5CG8, 6CG8 

Two new nine-pin miniature type 
receiving tubes, each containing a 
medium-mu triode and a sharp-cutoff 
pentode in one envelope, have been 
announced by RCA. The tubes, the 
5CG8 and 6CG8, are designed especially 
for use as combined oscillator and 
mixers in television receivers using an 
intermediate frequency of approximate- 
ly 40 mc. 

A feature of these tubes is a cathode 




120 



having two leads (see base diagram) 
connected to separate base-pin ter- 
minals. This arrangement reduces the 
effective cathode-lead inductance, there- 
by minimizing input loading effects of 
the pentode mixer unit. This also makes 
it possible to eliminate a common re- 
turn for the input and output circuits 
of the pentode mixer and thus minimize 
interaction between the two circuits. 

The low capacitance between grid 1 
and plate minimizes feedback problems 
often found in mixer circuits operating 
at an if of 40 mc. Feedback problems 
are especially troublesome on channel 2 
because of the small difference between 
the channel frequency (54-GO mc) and 
the if. The low value of output 
capacitance permits the tube to work 
into a high-impedance plate circuit with 
resultant increase in mixer gain. 

The 5CG8 and 6CG8 are highly useful 
in the design of AM-FM receivers. The 
pentode unit may be used in the AM 
section as a pentode mixer to provide 
high gain and in the FM section either 
as a pentode mixer or as a triode- 
connected mixer, depending upon signal- 
to-noise considerations. The triode unit 
of these tubes makes a satisfactory 
oscillator for either the AM or the FM 
section. 

The 5CG8 is like the 6CG8 except 
that it is designed for series-string 
operation, having heater requirements 
of 4.7 volts at 600 milliamperes. The 
6CG8 draws 450 ma at 6.3 volts. 

2BN4, 6BN4 

Medium-mu triodes of the seven-pin 
miniature type, the 2BN4 and 6BN4 
are designed especially for use as rf 
amplifiers in grounded-cathode circuits 
of vhf television tuners. 

The 2BN4 and 6BN4 each have a 
transconductance of 6,800 micromhos, 
permiting high gain and reduced equiv- 
alent noise resistance. The double base- 
pin connections (see base diagram) for 
both cathode and grid reduce the effec- 
(Continued on page 124) 

RADIO-ELECTRONICS 



www.americanradiohistorv.com 



6* na-*205G1 



75H^200G1 



.For dependable replacement 

viilik 




12 types — ratings from 

65 ma to 500 ma — meet 
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250 m~f3D8G1 




300 E*~-S32G1 





400 ma (ccrpac 



SELENIUM 



RCA SELENIUM RECTIFIERS 

are manufactured to give 
long and dependable 
performance. This 
dependability is made possible 
through new, advanced design, careful 
selection of production material, and thorough 
quality control in manufacture. The new, 
open design permits greater heat dissipation 
. . . no possibility of center "hot spots. 19 

RCA SELENIUM RECTIFIERS are a 

dependable replacement line because they are 
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Now available through your RCA distributor! 



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MAY, 1956 



RECTIFIERS 5g5[ 




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CltCTBONtC COMPONENTS 




121 



www.americanradiohistorv.com 



Align in IW 




// 














WESTON Simplified Method 
of Visual Alignment 



X "^bZu. • — ft" 

J^^^~ ""^J^ / ^^"-^ 



4 




Conventional Method 
of Alignment 




Mcdbl <965 WESTON Calibrator $199.50 ntt 

!■■■■■■■» 



122 



■■■■■■■I 

RADIO-ELECTRONICS 



www.americanradiohistorv.com 



Simplified WESTON method makes aligning 
quick-easy-profitable for every serviceman! 



There's real money in alignment . . . now 
that it's no longer necessary to use compli- 
cated, time-consuming methods. The Weston 
method is so quick, so simple, any serviceman 
can complete any alignment job in one hour 
maximum. 

Note the simplicity of the hook-up illus- 
trated at the loft, in which the calibrator is 
not connected to the circuit under test. 
With only two simple connections to the 
receiver, oscillations encountered in conven- 
tional methods are entirely eliminated. Fur- 
ther, there is no disappearance of markers at 
trap frequencies. Z-axis modulation of the 
scope provides accurate intensity markers on 
the response curve under conditions where 
beat note markers would not be visible. Re- 
sponse curves are not disturbed. Annoying 



trimmer touch-up on trap circuits is min- 
imized. (See marker presentations shown 
below. ) 

All you need to #lign simply, quickly, and 
get the big profits from this constantly in- 
creasing class of work are the WESTON 
Calibrator and Sweep Generator, and the 
Weston Oscilloscope or any scope with provi- 
sions for Z-axis intensity modulation. 



SEND for CATALOG NOW! A new catalog 
describing this simplified method end the 
instruments used, is available fcr the asking. 
Also included are descriptions of other 
Weston Test equipment including - Model 
980 Volt-Ohm-Milliammeter $42.50 net - 
Model 982 VTVM at $69.50 net - Model 981 
Tubechecker at $199.50 net. Send for your 
copy now. 




il 
II 




Simultaneous marker presentation of 
video and sound carrier frequencies 
(positive intensity markers)* 



Simultaneous marker display of video 
and sound carriers ( negative intensity 
markers). 



Note that witfc intensity markers 
there is no possible misinterpre- 
tation with spurious resDO&ses. 




WESTON 



WESTON Electrical Instalment Corporation, 614 Frelinghuysen Avenue, Newark 5, N. J 
A subsidiary of Daystrom, Incorporated 




m 



i 



MAY. 



1956 



123 



www.americanradiohistorv.com 



more 
Cannon lines 
now available 
at jobbers' 
shelves! 





When you write for our catalogs. . . Please refer to this magazine or Dept. 144 
_ „ aSJfc CANNON ELECTRIC COMPANY 

(^ T \TII7Tey71 rariTirT?^ mk 3209 Humboldt St.. Los Angeles 31. California 

~a-r-l_t_ILt J^/_>_l LrL-K^JiJ 1W4# Factories in Los «n9(l»i East Haven; Toronto 

Canada; London. England. Representatives and 
distributors in all principal cities. 



SENSATIONAL 



... is the word for the Miller 
#595 NEGATIVE MUTUAL 

COUPLED BROADCAST 
BAND-PASS DIODE TUNER 




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The most amazing High Fidelity Broadcast tuner ever 
offered to music lovers anywhere. High Fidelity fans 
will be pleasantly surprised with the tonal quality, 
selectivity, and sensitivity of this marvelous tuner. 
The frequency response is limited only by the audio 
system used. Freq. Range 540 KC to 1700 KC. 

A beautiful Black or Ivory bakelite cabinet houses the 
tuner with a Richlow brass etched panel for the 
escutcheon. Both combine to complement any decor. 

Like all Miller products this #595 tuner is guaranteed 
to perform to your satisfaction. Buy from your Radio and 
TV Parts Distributor, or High Fidelity Dealer, 

^^"^ #595 Tuner net price only $1 9 •50 
plus excise lax. 

SEE YOUR DISTRIBUTOR FOR 
LITERATURE OR WRITE DIRECT 



J. W. MILLER COMPANY 

5917 S. MAIN ST., LOS ANGELES 3, CALIF. 





COYNE 

trains you 
in spare Time 



Only from famous COYNE do you get this 
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FOUNOED 1899 



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* T i5iJ N J CAL TRADE INSTITUTE OPERATED NOT FOR PROFIT 
SOO S. Paulina De pt. 56-HT-4. Chicago 12, Illinois 

COYNE FXECTr"icI\l" SCHOOL 
Television Home Training Div. 
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Send FREE BOOK and details of your Television 
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Name 

Address _ 

City 



^State_ 



124 



NEW TUBES AND TRANSISTORS (Continued) 
tive lead inductance and resistance with 
a resulting reduction in input conduct- 
ance. The special basing arrangement 
of these tubes permits excellent isola- 
tion of input and output circuits, 

2BN4, 6BN4 

neutralization and short, direct connec- 
tions to the base-pin terminals. 

The 2BN4 is like the 6BN4, both 
announced by RCA, except that it is 
designed for series-string operation. 
Its heater requirements are 600 miHi- 
amps at 2,1 volts. The 6BN6 draws 
200 ma at 6.3 volts. 

Characteristics as a class-A amplifier 
are as follows: plate voltage, 150; 
cathode-bias resistor, 220 ohms; ampli- 
fication factor, 43; plate resistance 
(approximately), 6,300 ohms; trans- 
conductance, 6,800 micromhos; plate 
current, 9 ma; grid voltage (approx- 
imately) for plate current of 100 micro- 
amperes, — 6, 

Service-designed tubes 

G-E has added six more popular 
receiving tube types to its "service- 
designed" line (see photo). These tubes, 
G-E states, provide greater safety 
factors than called for in the standard 
product and thus perform well in most 
circuits. 

The six new service-designed types, 




and the improved features of each, are: 
1X2-B — A tungsten shield post con- 
struction alleviates filament pullout. 
An improved filament coating gives 
better electron emission. A flyback 
operation life test insures quality. 

6AL5 — New heater construction pre- 
vents flash burnouts by initial surge 
current. 

6BK7-A, 6BQ7-A and 6BZ7— Have 
construction features for greater heater 
reliability and freedom from heater- 
cathode shorts in cascode amplifiers. 
High zero-bias mutual conductance for 
improved fringe-area reception. 

6CB6 — A special alloy screen grid 
handles increased heat dissipation found 
in some video and if amplifier circuits 
and prevents control-to-screen grid 
shorts. Special mica spacers reduce 
interelement leakage and reduce age 
troubles in some television circuits. 
This tube also has a high zero-bias 
mutual conductance. end 

RADIO-ELECTRONICS 



www.americanradiohistorv.coiTi 



m 




Patents 



PULSE CALIBRATION 

Patent No. 2,719,232 

Robert W. Ehrlich, W. Orange, N. J. (Assigned to American Telephone & Telegraph Co.) 




This describes an accurate method for calibrat- 
ing a low-frequency pulse generator without 
using an oscilloscope. 

To calibrate, the measuring circuit (including 
the galvanometer is plugged into connector J. 
(See Fig. 1.) When impulse relay RY is ener- 
gized by the pulse generator (as shown), the 



During a pulse the voltage across the meter 
will be a combination of ac from the line and dc 
from the battery. Now if the pulse rate (pus) 
is an exact submultiple of 60 cycles, the break 
will occur at an identical point on the voltage 
waveform across the meter. For example, assume 
a pps of 30. Then the break will occur ovce for 



D ,+ 



IMPULSE RCLAY 

3> 



■hL 



PULSE GEN 



CAL PPS 



negative battery terminal biases the cathode of 
meter rectifier D so it conducts and shorts out 
the meter. It is only during a "break" between 
pulses that the meter can deflect. 



/WVAAA- 



30 PPS -25 % BREAK 



WY/UAA/l- 



15 PPS -12.5 % BREAK 



each two cycles of line voltage (Fig. 2). Because 
of the submultiple relationship, the make and 
break of the relay will occur at identical points 
of every other sine wave, so the meter will show 
a steady deflection. If this relationship did not 
hold, the break would occur at different parts of 
the ttave and the meter current would vary 
with time. 

The pulse generator netds only a rough adjust- 
ment for frequency, that is. only an approximate 
calibration. Then the operator sets a control 
until the meter remains perfectly steady. This 
indicates that the pulse rate is some submultiple 
of 60, for example 30, 20, 15, etc. 



Fig.2 



CRYSTAL DISCRIMINATOR 



Patent No. 2,724,089 

John Huston, Fair Lawn, N. (Assigned to Allen B. DuMont Labs, Inc.) 



A frequency discriminator measures or indi- 
cates frequency deviation. Ordinarily the dis- 
criminator puts out zero voltage at a standard or 
center-value frequency. When the frequency 
shifts in one direction, the output is positive; 
when it goes in the other, the output is negative. 
The output voltage may be used as a control sig- 
nal to control an oscillator and prevent it from 
drifting from its assigned frequency. 

In this discriminator circuit a crystal is in 
series with impedance Z (about 1,2000 ohms), to 
form a voltage divider. The voltage across each 
of these elements is rectified by a separate diode 
and combined and filtered to produce a dc control 
signal at the output terminals. The output of Dl 
is always positive while that of D2 is always 
negative. At the chosen center frequency f it , the 
crystal and impedance Z have equal impedance, 
so the rectifier outputs combine and cancel. This 
frequency f Q , must be inter mediate between the 
series-resonant frequency f 8 of the crystal and 
its parallel-resonant frequency fp. A crystal has 
minimum impedance at frequency f s and maxi- 
mum at f p . 

At frequencies above f 0 , the crystal has the 
greater impedance and Dl has" the greater out- 
put. Thus the control voltage must be positive. 
It will be negative at frequencies below f Q be- 
cause D2 has greater output. This control volt- 
age is fairly linear between f« and fp. 



DISCRIMINATOR 



LOW- PASS 
FILTER DC 

. C0NT 

vWH 




I 



A trimmer neutralizing capacitor balances out 
the capacitance of the crystal holder to some 
extent and thus adjusts f P as desired. For any 
crystal, series-resonant frequency f 8 remains 
constant. 



Patent No. 

Walter Monroe Jonas, No, Iter gen, N. J. (Assig 

A good wire connection is ordinarily made by 
soldering. This is easy and convenient when suit- 
able soldering iron is handy, but there are occa- 
sions when a substitute method is required. For 
example, a solderless connection has definite ad- 
vantages from a military viewpoint or during 



SOLDERLESS CONNECTOR 

2,716,226 



fd to Reiner Electronics Co., Inc., New York) 

civil emergency when no power is available. 

The method shown here requires only a screw- 
driver. The diagram illustrates one form of sold- 
erless connector. Screw S is made of somewhat 
smaller diameter than the bore or threaded metal 
cylinder C into which it is to fit. The wires to 



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125 



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DON'T 
, THROW 
m OLD 
J* RADIOS 
AWAY! 

Here's the data you need 
to fix old sets FAST — good as new 

Just look up the how to do it data on that old radio 
y<»u want to fix I 

Four times out of 5, this giant, 3^-pound, 744-page 
Chirardi KAD10 TROUBLESHOOTEK'S HANDBOOK 
gives exactly ihe information you need to fix it in a 
jiffy. Tells what is likely to be causing the trouhle 
. . . shows how to fix it. No useless testing. No wasted 
time. Handbook covers common troubles and their 
remedies in practically every radio receiver model made 
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can lie made to operate perfectly for years to come. 

THE ONLY GUIDE OF ITS KIND! 

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Included are common trouble symptoms and their rem- 
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lU'A. Silvertone. Sparton, Stromberg and dozens more. 
Gives liow-to-do-it data on SPECIFIC jobs — NOT gen- 
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component data, service short cuts, etc, no longer avail- 
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a— TRY IT 10 DAYS ... at our risk!..., 

■ Dept. R.E.-56, RINEH ART & CO., Inc. ■ 
J 232 Madison Ave., New York 16, N. Y. ! 

■ Send Ghirnrdi's RADIO THOUBI.ESHOOTER'S ■ 

■ HANDBOOK for 10-day free examination, if I decide ! 

■ to keep book, I will then remit the full price of only i 
" S6.50 plue a few cents postage. Otherwise. I will ■ 
I return book postpaid and owe you nothlne. J 

■ ■ 
5 NAME ■ 

: : 

■ ADDRESS , a 

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• Outaid* U. ti.A.—Pric* $7 oo, C a»h o,,l y . Same rrtur'n'priwiiw j 

Rinehart Honks are sold by leading: book stores 

126 




TOWERS 



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{State type and model) 
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Address.. 
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P. 0. Box 549) • Tampa, Fla. 



Telephone 4-2171 



(Continued) 



be connected are pressed together and held tight- 
ly between the threads as the screw is driven 
into the bore. Actually the wires are bent into 
a corrugated pattern and make an excellent elec- 
trical and mechanical splice. Loose wire ends 




are snipped off and the connection taped or pro- 
vided with an insulating jacket. 

If necessary, these wires can be separated 
without damage. 

TIRE PRESSURE ALARM 

Patent No. 2,727,221 

Ed w ward A. Sprigg, E. 
Orange, N. J. 
( Assigned to Breeze Corporations, Inc., 
Union, yV. J.) 

Tires on al! types of vehicles — especially heav- 
ily laden trucks and trailers that travel at high 
speeds — -must be inflated to a certain minimum 
pressure for safety and reduced wear. This is a 
radio warning system which notifies the driver 
when tire pressure falls too low. Tiny radio 
transmitters, located on each wheel, are actuated 
by a switch that closes whenever the pressure of 
a tire falls below the predetermined minimum. A 
receiver in the cab of the truck receives these 
impulses. 

The switch that operates by the tire pressure 
is described in the patent notice. Briefly, when 
the tire loses air, a spring drives a plunger to 





-VALVE STEM 



close switch contacts. Actual transmitter or re- 
ceiver circuits are not described in the patent, 
but they must be tiny and may radiate very weak 
power. A transistorized printed-circuit network 
would seem practical. 

As shown in the diagram, each tire is equipped 
with its own transmitter and antenna. A receiver 
in the cab picks up the signals. The inventor 
suggests a different frequency for each tire and 
perhaps colored lights on the dashboard to indi- 
cate which th-e is at fault. end 




"Well you shouldn't have any 
trouble with that .0001-/xf bypass, 
in an overrated replacement." 



more 
I put 



RADIO-ELECTRONICS 



www.americanradiohistorv.com 




THE NEWEST! 

CORNER 
SPEAKER 
CABINET KIT 

kitform of the original 
corner speaker horn 
one. of 39 new units ! 

slightly higher west ond south < 



Technotes 






99 North Uth Street, Brooklyn II, N.Y 

largest manufacturer of cabinets and kits for hi fi 

o division of G & H Wood Products Co. Inc. 



* GPR 
1 90 





IN CANADA 
TMC Canada, LTD. 
OTTAWA, ONTARIO 



■communications receiver 

• Six bands; .54 to 31 mc, AM, CW, MCW (FS 
with convert.) 

• Accurate main tuning with full elect, bandtpread 
e Ferrite transformer, 75 ohm unbal. to bal. input 
e One microvolt sensitivity on hf bands 
e Image ratio; better than 60 db 
e New Audio Selectivity design with variable 

bandwidth. 

• 110 VAC 50/60 cy. appr. 90 Woits 

Complete Receiver *395 net 
Matching spkr $16.00 
WRITE FOR BULLETIN N-179 

The TECHNICAL 
MATERIEL 
CORPORATION 

MAMAHONECK, 
KEW YO« 



HORIZONTAL OSCILLATOR 
COIL 

Recently I was stuck with a defective 
oscillator coil used in a conventional 
horizontal multivibrator circuit (Fig". 
1). With no replacement on hand and 
faced with the customer wanting the 
set in a hurry, I made up a new 
unit using a width coil having an age 
winding. The Merit MWC-1 was perfect. 

BSN7-GT 

.005 




With the several windings and taps 
available, there are many ways of con- 
necting them to get the required amount 
of inductance. Fig. 2 shows how the 
width coil was connected with the best 
results as a replacement for the oscil- 

i- 1/2 I*?* 
/I 6SN7-GT ? 




lator coil. This done, it was just a mat- 
ter of adjusting the circuit on frequency, 
using the slug in the width coil. No 
other changes were necessary. There 
were no mechanical difficulties since the 
replacement is about the same size and 
mounts in the same manner as the orig- 
inal. — Carl Lindfors 

MAJESTIC 7P420 RADIO 

If the 50B5 in this receiver is gassy, 
the tubes will frequently burn out. 
When this appears to be the trouble, re- 
place the 50B5. The heater voltages 
should be checked to see if they are 
normal after a good tube has been 
placed in the receiver.— E. M. Breck- 
enridge 

PHILCO C1908 RADIO 

If a howl is heard after a defective 
output transformer has been replaced, 
reverse the plate connections of the 
transformer primary. 

If full volume produces excessive dis- 
tortion, with normal sound at average 
volume, the output transformer may be 
defective. This can be checked by meas- 
uring the voltage at the plates of the 
7C5's. There will be equal voltages at 



ATLAS SOUND CORP. 
1443 - 39 St., Brooklyn 18, N. Y. 

Send FREE Buyer's Guide to save me money on 
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and accessories. 



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_Title 



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HOW to SAVE MONEY 
on LOUDSPEAKERS 
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find out how ATLAS 
proves that better 
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at lower cost to you. 
Depend on world- 
famous ATLAS — the 
complete quality line 
with specialist know* 
how since 1930. 

J SOUND CORP. 

1443-39th. Street, Brooklyn 18, New York 

In Canada Atlas Radio Corp.. Lid „ Toronto, Ont 

127 



www.americanradiohistorv.com 



CUSTOM-BUILT CABINETS i FACTORY » YOU 



3 LEADING 1956 STYLES m genuine 
Mahogany or walnut (blond 10<%> extra) 

• Ready chilled for any #630 TV chassis 
and cutout for any 10". 17". 19". 20" or 
21" picture tube at no extras in price* Also 
supplied with undt- tiled knob panel for any 
other TV set • EVERYTHING NECESSARY 
for an easy perfect chassis and CRT assem- 
bly Is Included • Each cabinet is delivered 
complete as pictured with mask, safetv 
glass, mounting brackets, backboard, hack- 
cup, hardware and assembling instructions 

• Each cabinet is shipped in an air cush- 
loned carton from FACTORY to YOU! 



WESTCHESTER S 88 70 



MANHATTAN 



GEM $35-91 




GEM 

also 
available 
for 

24" or 27" 
picture tube 

$59.54 



H-25" W-26" D-22" 




M-41" W-26" 0-25' 



MAN- 
HATTAN 

also 
available 
for 

24" or 27" 
picture tube 

$79.22 




DUMONT OR THOMAS PICTURE TUBES 

BRAND NEW in Factory Sealed Cartons — With a Full Year Guarantee 

17"-*22«|2r;^J32- 2 '|24k^48 M |27;.fe $ 74 J ' 



tubular condensers !s°c FLYBACK TRANSFORMER 

TOP QUALITY— Equally as good for TV or ttarlio Work. f _ . . . 



Example of 
,005 — 100V 
.01 — 400v 
.02 — lOOv 
.047— 400v 



,alue we offer 
4c 
5c 
5o 
7c 



A — 400v .„ 9c 

.25 — 400v _.l2c 

.005— 600v 7c 

.01 — 600v 8c 

.02 — 600v 8c 

20 mfd— I50v 27c 

40/40 mfd— I50v 38e 

50/30 mfd— I50v 39c 



.047— COOv lists at 36c 

.047— 600V _ 9c 

.1 — 600v 12c 

.25 — 600v 14c 

,001 — lOOOv lie 

.01 — 1000V 14c 

.035— lOOOv 16c 

.05 — lOOOv 18c 

.1 — lOOOv 22c 

.5 — 400v -...28c 

8 mfd — 150v 26c 

40 mfd — 450v 49c 

80 mfd — 450v 56c 



Latest single 1B3 type, for the 21" and all 70° 
Picture Tubes. It is similar to the popular NO. X-053 
and goes up as high as 16KV. With it you receive 
easy-to-follow instructions and schematic 
diagrams that apply to build, convert or i 
prove practically all makes of TV Recei" 



naiic _ _ 

^-$4.86 



f^Th 



COSINE DEFLECTION YOKE 



-MICA & CERAMIC CONDENSERS 

Values up to 85c each 
5, 10. 51. 56. 82. 100. 120. 150. 220. 
270. 330. 390. 470. 510. 680, 1000. 1200. HC 
1500, 3900, 6800 MMF Your choice w ~ 



CARBON RESISTORS 



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any ohmage from 2.2 onins to 10 me? in the desired 
tolerance. Deduct lOQfo on lots of 100 or over. 




The latest achievement in the 70° type, with com 
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Set. in brilliance, clarity and sweep. This is the 
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it you receive easy-to-follow instructions 
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18KV FLYBACK TRANSF 

This new Flyback Transformer now makes 9O 0 
conversions easy on any make TV Set. Customers 
report excellence on 24" and 27" TV sets built or 
converted with this Transformer. 
Instructions and schematic 
diagrams included 



Va WATT. 5%.. 


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10%. . 


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1 WATT, 5%.. 


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2 WATT. 5%.. 


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f NE 



COSINE DEFLECTION YOKE 



/NEW 90 ' TYPE, with complete wired network. It 
I solves ail problems formerly somrht for. in 90° 
I Yokes for undistorted clear pictures and ease of 
I overall sweep. Instructions and schematic - m AA 
I diagrams- included for building, replacing \ C MX 
1 and converting - *3 



V an< 



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1 oz. mag. on 3" to 6", heavier mag. on 8" & 12" 



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List slashed 
$30.95 to 



14 



.32 



3-Way Portable #1877 




List slashed $ 
$36.95 to 



16 



* Colors on #47 1 , 27 1 and 1877 are Walnut, Ivory, Ebony and Maroon. In event we cannot supply specified 
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SPECIAL TV PUBLICATIONS 



INSTRUCTIONS for 

building any £ 630 TV Receiver from the Y I postpaid 



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building any £ 630 TV 
original 10" to the If. test 27 ".. 



90 c TV CONVERSION MANUAL, how to con- 
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50* 



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50* 



HINTS FOR BETTER PERFORMANCE on your 
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50* 



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Cascode Tuner in any make TV set 



25* 



postpaid 



A.G.C. STEP-BY STEP INSTRUCTIONS, how 

to add A.G.C. to any make TV Receiver 



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FREE CATALOG mailed on request 

, out* 




SUPER DE LUXE 

31 TUBE 
#630 TV CHASSIS 



#630 SUPER DELUXE 31-TUBE TV KIT 

OPERATES 16" to 21" PICTURE TUBES • Engineered 
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added features • FULL 4MC BANDWIDTH • CAS- 
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ER POWER TRANSFORMER • KEYED AGC • 12" 
SPEAKER • CONDENSERS and RESISTORS at rated 
capacities and tolerances. You receive a COMPLETE 
SET of PARTS and TUBES, everything needed is in- 
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enjoy building it with "LIFE-SIZE easy to follow 
step-by-step ASSEMBLING INSTRUCTIONS" included 
with each KIT. 



Slashed to 



99 



.99 



Similar KIT for 24" or 27" CRT $ 
slashed to 



110 39 J 




,#630 D t u L p 0 E ; E TV CHASSIS 

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COMPLETE READY TO PLUG IN AND PLAY 

Similar in features to the 10" to 21" TV KIT above. 

Slashed to$1 42^ 7 m » 

A ^T^H Hess CRD 



#630 5 TECHMASTER 



COMPLETE LINE AT SPECIAL PRICES 
Catalog mailed on request 



STANDARD CASCODE TUNER 



For better all around performance 
Complete with tubes and Brooks CASCODE 
MANUAL with step-by-step instructions and 
1 extra harts needed. 



jRtlTN. 



21" TV CONVERSION KIT— 

NOW . . . Anyone with even a limited knowledge 
of TV — can Convert any Size, any Make TV RE- 
CEIVER to operate 21" or any 70° Picture Tube. 

COMPLETE SET OF ESSENTIAL PARTS includes 
matched set of Todd 70° COSINE DEFLECTION 
YOKE and TODD HV FLYBACK TRANSFORMER, 
FOCALIZER 20KV FILTER, DRIVE TRIMMER, 
LINEARITY COIL, CONDENSERS, RESISTORS. 

Your $10-97 ListPrke $315 ° 
price... 



M3 



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Step-by-Step Instructions & Diagrams. 



Similar Kit for 24", 27" or any 90° CRT 



s 15 



98 



UNIVERSAL SSSAiS BRACKETS^ 



Complete — 
Including band 
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picture tube 




PULSE KEYED AGC KIT 



Finest, most accurate and the easiest Kit to install 
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Improves performance and insures a steady picture 
on all channels. 

COMPLETE SET OF PARTS 

Including 6AU6 tube & Instructions 



$2-99 



BROOKS RADIO & TV CORP., 84 Vesey St., d*«. New York 7.N.Y. 



TELEPHONE 
COrtland 7-235$ 



123 



RADIO-ELECTRONICS 



www.americanradiohistorv.com 



TECHNOTES (Continued) 

normal volume levels, slightly different 
at high volume levels. — Lyle Bnggs 

PICTURE FLUTTER 

A common cathode lead impedance in 
a combined first audio and age circuit 
often produces picture flutter. A typical 
circuit (Emerson 120166-D) is shown in 
Fig. 1; Fig. 2 shows the equivalent cir- 
cuit containing resistance, inductance 

6AY6 TO AUDIO OUTPUT 




rit.i 



and capacitance. A voltage is developed 
across this impedance and impressed on 
the age line, regardless of the amount 
of age filtering. Thus, the age voltage 
will vary with sound volume, causing 
the gain of the rf amplifier to vary at 
the audio rate and the picture to flutter. 




The cause of this trouble is often a 
cold solder joint that creates a high- 
resistance path in the cathode circuit. 
Sometimes it is merely a very long lead 
that can easily be shortened or supple- 
mented with a braid from the cathode 
terminal to ground. To check, turn the 
volume on full and watch for this effect. 
— James A. McRoberts 

RCA TELEVISION SETS 

To improve sound and picture gain in 
the early RCA split-sound receivers, 
change the first and second picture if 
cathode resistors from the original 120 
ohms to 80 ohms. This modification is 
especially helpful in fringe areas. Also 
move the sound takeoff on trap T103 up 
two turns on the coil. This provides ad- 
ditional 21-mc sound signal for the if 
amplifier. Realign the set after this 
change. — W. S. Ross 

RCA 21-INCH COLOR TV 

In the 21-CT-661U and 21-CT-662U 
receivers color edges may be improved 
by a change in the 6AZ8 bandpass am- 
plifier stage. Resistor R232 (Fig. 1) 
should be changed to a 2,700-ohm 
watt unit. The bandpass and first video 
amplifiers should then be realigned to 
give the response curve in Fig. 2. 

A further change was made in the 
bandpass amplifier to make its bias 
track better with changes in burst level. 
This is desirable in areas where both 
strong and weak signals are encoun- 
tered. Disconnect pin 2, the screen grid 
of the bandpass amplifier, from ter- 
minal A of T113, the bandpass trans- 



C-D features the 

NEW COMPLETE line 
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Vibrators 




Here is everything needed 
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communication vibrator 
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EACH application! 




Ten Types Provide Complete Replacement for 
ORIGINAL Communication Equipment 



New 


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'Old No. 


6 volt 


12 volt 




S7IS 


6715 


5515 


5718 


6718 


5516 


5721 


6721 




5722 


6722 


★ 


5725 


6725 


★ 


saos 


eaos 


5605 


5820 


6820 


5620 


5821 


6821 


5621 


5822 


6822 


5622 


5824 


6824 


* 



For Specific Applications, see the SEW C-D Vibrator Guide 



Cornell-Dubilier Vibrators 

PLANTS IN SOUTH PLAINFIELD. N J.: NEW BEDFORD. WORCESTER 

and Cambridge, mass.: providence and hope valley. m.t.t 

INDIANAPOLIS, IND.: SAN FOR D AND FUOUAY SPRINGS. N.C.: 
SUBSIDIARY! THE RADIART CORPORATION. CLEVELAND. OHIO 



SUBSCRIBERS 



If you're moving, please don't forget to send us your old address as it 
appears on the address label of your current copy of the magazine, 
including the numbers shown beside your name, as well as your new 
address. If we receive this information before the 20th of the month, 
you will continue getting the magazine without interruption. Your co- 
operation will be most helpful and greatly appreciated. 
We, too, have a new address: 

Subscription Department 

RADIO-ELECTRONICS 
154 West 14 St. 
New York 11, N. Y. 



MAY, 1956 



129 



www.americanradiohistorv.com 




"101" USES —No need to leave appliances for work or pleas- 
ure behind. Take them along. Use them on business trips, 
camping, at the cabin, hunting, etc. Just plug Trav-Electric 
into cigar lighter on dash. Plug appliances into Trav-Electric 
That is all! 

6 MODELS— for both 6 and 1 2 volt batteries. All models 
change battery current fo 110 volt A.C. 60 cycle, same 
os at home. Sixes 2" x 2" x 3Va" to 4" x 5" x 6". 
Capacities: 10 to 125 wafts. Fully guaranteed. Lis! 
prices: from only $11.95 to $54.95. 

See your Jobber Salesmon, or write for name of nearest 
Jobber. 




Dictating Machine 



Heating Pad 



Phonofnph 



TERADO COMPANY 

Mfrs.of Electronic Equipment Since 1927 



1057 Raymond Ave., St. Paul 14, Minn. 




Hand Vac. 



In Canada write: AHas Radio Corp., Ltd. 
50 Winqotd Ave., Toronto 28, Ortt. 
Export Sales Division-. Scheel International, 
Inc., 4237 N. Lincoln Ave., Chicago 18, 
III., U. S. A. —Coble Address— Harscheel 




"That third guy? He's the 
serviceman carrying the 
JENSEN NEEDLE!" 



WORLD'S RADIO TUBES 

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EDITORS and ENGINEERS, Ltd. 
S u miner! and 3. California 




TECH NOTES (Continued) 

former, and re-connect to the 140-volt 
bus at pin 7 of the age amplifier. Con- 
nect an 18-megohm resistor from ter- 

TD BURST KEYER & DEMOD DRIVER 

1/2 6AZ8 TI13- BANDPASS TRANS 
BANDPASS AMPL 



fill 

minal A of T113 to the junction of 
R298, R217 and R218.— RCA Television 
Service Tips 

MAGNAVOX-COLLARO 45 RPM 

If the 45-rpm adapter for the above 
changer fails to function, it can usually 
be repaired easily in the field. The pro- 
cedure for checking is: 

1. Remove the retaining ring on the 
bottom of the center shaft. You can now 
remove the metal base, the bottom sec- 

,R£COR0 SHELF 

STOP 




'SEPARATOR 



RECORD SHELF 

tion of the adapter and the large coil 
spring (see diagram). Caution: Do not 
lose the brass shim on the hub of the 
center shaft. 

2. Remove the two screws holding the 
top and center sections together. These 
are accessible from the bottom of the 
center section. 

3. While holding the two sections ver- 
tically, lift the top section straight up 
so as not to disturb the springs holding 
the plastic shelves in position. 

4. Loosen the elastic stop nut and 
clean the record separator parts with 
carbon tet so they are free of dirt and. 
will slide easily. (Service cleaners other 
than carbon tet are safer and should be 
used. — Editor) 

5. Make sure both springs are in 
place, tighten the elastic stop nut until 
there is no play in the record separators 
and then back off about ^4 turn. 

6. Reassemble the adapter, following 
the reverse order of the disassembly in- 
structions. — Magnavox Service News 
Letter end 



130 



RADIO-ELECTRONICS 



www.americanradiohistorv.com 



to 
be 




buy 

VOKAR 

the original- 
equipment 
VIBRATOR 



1 



V OKAR 

VIBRATOR 




Leading manufacturers of 
original -equipment auto -radios 
specify Vokar vibrators as com- 
ponents for installation on the 
production-line. Why? They're 
sure Vokar quality never varies 
—will always contribute to top 
performance demanded of to- 
day's radios. 

You too can depend on Vokar 
vibrators— for sure starts, longer 
life, silent operation. For all 
replacement jobs, buy Vokar 
Imperial or Quality Brand vibra- 
tors to be sure of satisfied 
customers. 

Now is the time to stock up on 
12- volt vibrators-ONLY TWO 
VOKAR IMPERIALS ARE 
NEEDED TO FILL ALL 
REPLACEMENTS! 



VOKAR — preferred by 
leading manufacturers of 
auto-radios. 




try 

This 

one 

VIDEO PEAKING 

Some power resistors have just 
enough inductance for plate loads in 
video amplifiers and are simpler than 
non inductive resistors plus separate 
peaking coils. This is often true of 
10- and 20-watt sizes from 2,000 to 
6,000 ohms, I have used ordinary 
Ohmite Brown Devils as loads for GAC7 
preamplifiers and an 829 df fleeting a 
5CP1 in a 5-mc oscilloscope for fast 
transients, I now am using 3 ,000 -ohm, 
20-watt IRC type 2D resistors as loads 
for 1625's deflecting a 5CP1 or 5ABP1 
in another wide-band scope. This in- 
strument uses feedback and reproduces 
a 450-kc square wave well. 

Power resistors below 2,000 ohms 
may have too much inductance. A 1,000- 
ohm, 20-watt resistor as load for 
parallel 807's to drive an rf bridge 
rang badly when hit by a square wave 
and would have caused oscillation in a 
feedback amplifier. — A. H. Taylor 

FILTER CAPACITORS 

A defective filter capacitor is sus- 
pected whenever a radio or TV receiver 
has loud hum. The usual method for 
locating the bad unit is to place a test 
filter capacitor across each unit in ✓the 
set, one at a time. When the hum is 
eliminated, the bad capacitor has been 
found. 

Instead of placing a test capacitor 
directly across each suspected unit, we 
use a testing aid that includes a 40-nf 
capacitor and 4.700- or 5,000-ohm resis- 
tor with a cutout switch as in diagram. 
The unit is placed across the suspected 
capacitor with the switch open. The 
resistor limits the charging current 



J WA* 

5K/IW 



40^4507 



VOKAR CORPORATION 
DEXTER 2. MICHIGAN 



into the test capacitor and eliminates 
costly burnouts of pilot light and 
rectifier tube in ac-dc receivers. After 
a second or two, when the capacitor is 
almost fully charged, the switch is 
closed. Another advantage of using 
this testing aid is that the suspected 
unit is usually not disturbed by the 
test. This avoids the annoying expe- 
rience of temporarily healing an inter- 
mittent capacitor which then is difficult 
to locate until it becomes defective 
again. — G. Sabin 

HANDY BENCH "TOOL" 

A very handy item for the radio-TV 
service bench can be picked up for 




American "501" 
Series Microphones 

Lightweight, rugged, easy to handle . . . 
true-to-life in fidelity of voice pickup. 
The new American "501" Series pre- 
sents a complete line of dynamic or 
carbon hand microphones to improve 
all types of voice communications. 

The attractive styling is completely 
functional . . . the gently cur i d case 
fits easily into the han<£ Positive opera- 
tion under all conditions is provided 
by a specially designed cantilever 
switch. The case is made of die cast 
aluminum to assure durability and 
minimum weight. 



There's a model for every need: 

i 

• Mobile 
Communications 

• Police 

• Shlp-to-Shore 

• Aircraft 

• Amateur 

To be heard and understood 
. . . start with an American Mi- 
crophone. Write for complete 
details and specifications to- 
day. Ask for Bulletin 501. 




ELECTRONICS DIVISION 

ELGIN NATIONAL WATCH COMPANY 
370 South Fair Oaks, Pasadena 1, Calif. 



MAY, 1956 



131 



www.americanradiohistorv.com 



PRE-SUMMER SALE! 

ELECTRONICS— OPTICS— TOOLS 

CDCCI ANY ITEM PRICED SI OR LESS 
rl\tt' WITH ANY * 10 ORDER! 

World Famous "KIT KING" Kits 

n PRINTED CIRCUITS 
KIT. Antic) . Printea cir- 



cuit board* w/l«y„ preci- 
sion* A-fJ reslsUwt,. Tnuisl- 
tmn diode*. I h sealed <1 
oils. Wt. 1/a lb. ReK. 5 15** 

f~] TEN Ml-F| KNOBS. 

«— ' AssUl. Crunume \W 
knurled bakelite. aluminum 
Inlav t.vueH. TUNING. AM. 
FM. BASS. TREBLE. PHONO. 
In poly U'ikb. wt. 1/3 lb. CI 
R«K. $3.30 5A 

rn 12 AC 'DC LINE CORDS 

' For all electrical usesf 
W/ sturdy molded Pluus. 
SUiek up at this low c-f 
price! Wt. 1 lb. ReK. S3 5X 



radio. TV. in- 
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1.1. 2.5. 3.5. 4 & 6 CI 
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radio. TV. appliance, in- 
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Some SOc ea. W t. I lb. CI 
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to £24. Asstd. colors. 
Ktrandlnu. lmulatlon. C1 
Wt. 2 lb. ReK. S4 * A 



1 0 ohms to 0.5 meKs. Switch 
* WW. toof Wt. 1 lb. CI 
Reg. $11 



n SO CERAMIC CONDENS- 
«— • ERS. Tubular, disc, but* 
ton. standoff types. 5 mmf. 
to .01 mf. hp to 1000 voits. 
Wt. i/a lb. CI 

CERAMICS. 

makes; lotyttes. 
50 mmf. to .oi ml"., to 5 kvV. 
TV men take note! . CI 
ReK $7 

J—| lOO COIL FORMS. Ce- 
•— 1 ramie & bakelite forms 
in a wide variety of shapes 
and sizes. Wt. 2 lbs. CI 
ReK. $25 * x 

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Chokes. RF. ANT.. OSC.. 
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L — ' Larue asst. wire, mould- 
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leads. Wt. 3 lbs. 
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*-» Submtniatures. 7. 8-Dln 

tiilnlatUres. 4 to Spina. 

Mica -Ailed & ceramic. Some 

shield base. Wt. 1 lb. CI 

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1 — Postage Ni«mp types. 2:> 
values! .00001 to .01 mf. 
to 1200 WVDC. Silver. 5<r 
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Asstd. values to 20.000 
ohms. Clarostat. Ohmite. 
1KC; tubular, candolun. CI 
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lOO mf.. to 450 V. Multi- 
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shop screws. ftprinKs. Krom> 
mets. etc. Hundreds of 
Items. Wt. 21^1 lbs. CI 
ReK. $15 ^ ± 



Wide variety: 

solder luKs. tie points. Set 

builders' must! CI 

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IN 

micro. totrele. 
push: mobile types, too! 
Some worth $2. Wt. Ct 
1 lb. ReK. $12 ' A 

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standard values. 1 watt 
Pre-cut leads. Wt. l/a lb. Cl 
ReK. $ 1 7 ^ A 



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screws. Wt. 2 lbs. 
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1 cycles: 3 ohm v.e. Used In hlKh- 
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□ FAIRCHILD Va" ELECTRIC DRILL. Pistol 'Krlp tvpe 
v. 'switch. Also 13 twist drills. ReK. $21 Jjj gg 



TRY THIS ONE (Coniinued) 

practically nothing from any iron works 
or dealer in structural steel materials. 
I have found that short lengths of steel 
I-beam are useful for many purposes 
in the shop. Mine are 4-inch lengths of 
material V\ inch thick and 3 inches 
wide with 1*4 -inch leg channels. I use 
them for propping up awkward chassis, 
for weighting reglued speaker cones, 
as soldering-iron rests, as temporary 
bookends and as anvils for light rivet- 
ing and hammering. 

I picked mine off the scrap heap of 
a local iron works, filed the ends smooth 
and sprayed them with aluminum Kry- 
lon. I've used them almost every day 
for the past several years. The four 
units that I have are probably the 
only tools in the shop that will never 
wear out and cannot be broken. — L. H. 
Wilson 

CHECKING 8-WAY SETS 

A variable voltage source is necessary 
to check three-way portables properly 
on ac line operation. Because of the 
low current drain of these sets a tube 
tester will serve the purpose while pro- 
viding isolation from the line to pre- 
vent shock hazards. 

Many tube testers have a blank socket 
that can be replaced by an ac type 
receptacle. The current is taken off the 
100- to 117-volt tap of the filament 
transformer with a 1 -ampere fuse in 
series with one side for protection 
apainst shorts. On other types of tube 
testers a simple adaptor using one of 
the tube sockets can be made up and 
the connections set up as for the 117- 
volt tube. 

By adjusting the line set control the 
vol tage ca n be r a i sed or lowered . A 
set that has a bad oscillator tube, 
rectifier or other troubles is easily 
detected because it will usually cut out 
when the voltage is lowered. — G. P. 
Oberto 

MODIF YING VTVM FILTER 

In the December, 1955, issue James 
Fred described a 400- and 1,000-cycle 
filter, to be used with a vtvm when 
aligning AM equipment. The article 
suggests connecting the filter to the 
coupling network between the first and 
second audio amplifier stages of a 
Heathkit ac vtvm. However, in this 



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95 

Kit 

Complete with 
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• Checks all capacitors for leakoge with 
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meter there is a feedback loop from the 
output of the second audio stage to 
the cathode of the first. Thus the filter 
will be inside the loop and its selec- 
tivity will be flattened. Hence the fil- 



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TIADI MAIK IfC. U.S. PAT. OFF. 

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132 



RADIO-ELECTRONICS 



www.americanradiohistorv.com 



TRY THIS ONE (Continued) 

ter may not yield its designed perform- 
ance. 

In my opinion, the best place to con- 
nect such a filter in the Heathkit vtvm 
is in the grid circuit of the 6AU6 first 
audio stage, as shown in the diagram. 
Here the filter is out of the feedback 
loop and will show its full selectivity. 
The 1-megohm resistor in series with 
the grid circuit prevents shunting of 
the filter by the low resistances of the 
divider chain on the higher voltage 
ranges or by a low-impedance source on 
the higher voltage ranges. Due to the 
high input impedance of the 6AU6 
stage, there will be but little change in 
calibration for normal operation. This 
can be easily compensated by the cali- 
bration pot. — Charles Edwin Cohn 

VERTICAL SYNC TRACER 

When it is inconvenient to use a 
scope for tracing vertical sync-pulse 
troubles, this handy little gadget, made 
from a pair of headphones and an 
extra test prod, can stand you in good 
stead. The sketch is self-explanatory: 
one lead of the headphone goes to the 
prod itself while the other side goes 
to a sheet of aluminum foil wrapped 
around the handle. The whole business 
can then be wrapped with a plastic 
insulating tape for safety in use. Only 
one direct connection is made to the 
circuit under test, thus avoiding load- 

70 PHONES 



TEST PROBE / 



LAYER Of ALUMINUM FOIL 



OUTER WRAPPING Of PLASTIC TAPE INSULATION 



ing the circuit. The return is through 
"body capacitance." 

When the probe is touched to an out- 
put portion of a functioning vertical 
oscillator, a distinctive 60-cycle click 
or thump will be heard, the frequency 
of which should vary as the hold con- 
trol is manipulated. 

In those sets which have a normal 
raster and picture, but will not stand 
still vertically, loss of sync is indicated. 
It is in these cases that we can use this 
tool to good advantage. Start at the 
point of sync take-off, whether it be the 
video detector or the last video if stage. 
At this point you should be able to 
hear a decided click or thump of the 
sync pulse so long as the blanking bar 
appears on the picture. Then touch the 
inputs and outputs of all tubes ; capaci- 
tors, resistors down through the sync 
separator, the sync amplifiers, and clip- 
pers, even the integrator until you find 
the points between which the pulse dis- 
appears. 

Just one word of caution. Often you 
will find a sync pulse on both sides of 
a blocking transformer when the fact 
is that the coupling coil is open. You 
can check to see if the click is sync 
or generated pulse by twiddling the 
hold control. If generated, the fre- 
quency will vary. Many times, as you 
follow the sync pulse through the chain, 
it does not disappear, but becomes 
weaker, due to a faulty tube or compo- 
nent. — H. L. Matsinger END 

MAY, 1956 



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133 



www.americanradiohistorv.com 



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558 CONEY ISLAND AVE. • B'KLYN 18, N ; Y. 




SQUELCH FOR S-81 RECEIVER 



We use a Hallicr afters S-81 receiver 
as a radiation monitor for dielectric 
heaths in our plant. We would appre- 
ciate details on an audio squelch cir- 
cuit that we can add to this receiver 
to control the background noise and 



6AL5 

RATIO OCT 



tors and pin 1 of the 6AL5 are lifted 
and connected to the arm of the squelch 
control as shown. 

The voltages and some resistance 
values may have to be determined 
empirically. Those resistors whose 



* £TT VitV— ^ — r 



Y9+ 



MIS 



6SL7-GT 

SQUELCH CONTROL AF AMPL 



TO OUTPU T 




hiss that are present when there is no 
signal on the antenna. — B. R., Boon- 
tony N. «/. 

The drawing shows how the Halli- 
crafters S-81 can be modified to include 
a squelch circuit similar to that used in 
the Monitoradio MR-32 and to the sys- 
tem described on page 82 of our Octo- 
ber, 1950, issue. 

The 6SQ7 af amplifier is replaced by 
a 6SL7-GT. The added components are 
enclosed within dashed lines. The 
grounds on the 47,000-ohm detector 
load resistor, the 2-fif storage capaci- 
tor, one of the 100-/*j"f balancing capaci- 



ADDED SQUELCH CKT 

values are likely to be critical are 
shown with a range of values. Select 
the optimum value by experimenting. 

The circuit is designed so that when 
no signal is applied to the set's antenna, 
the control tube conducts and develops 
a voltage drop across the resistor in 
its plate circuit. This increases the 
bias on the af amplifier and drives it 
to cutoff. When a signal comes in, a 
negative voltage appears on the grid 
of the control tube and cuts it off and 
permits the af amplifier to operate nor- 
mally. The squelch control sets the 
operating point for the circuit. 



Is there a simple converter that can 
be used with AM radios to receive 39.5- 
mc forest-ranger signals? If so, please 
print the circuit and show how the con- 
verter can be disabled so broadcast 



39-MC: CONVERTER 



R. S., 



stations can be received. — E. 
Centertown, Ky. 

Here is the circuit of a 39-mt* con- 
verter that can be used with auto or 
ac-operated broadcast receivers. A 




134 



RADIO-ELECTRON ICS 



www.americanradiohistorv.com 



QUESTION BOX 

crystal-controlled oscillator is used for 
stability. The oscillator may be oper- 
ated on any frequency between 38,000 
and 38,950 or 40,050 and 41,000 kc and 
still have the converter output come 
in on the receiver between 550 and 1500 
kc. 

In this circuit, the oscillator fre- 
quency is 1500 kc below the signal fre- 
quency so the receiver must be tuned 
to 1500 kc when the converter is being 
used. The crystal may be one of the 
James Knights series JK-H17, Bliley 
BH-0 type or equivalent. 

Coils L3, L4 and L5 may be CTC 
(Cambridge Thermionic Corp.) type 
LS3 30-mc coils. L2 is a 3-5-turn wind- 
ing* of No. 28 enameled wire close- 
wound over the ground end of L3. LI 
is a trap tuned to the converter's out- 
put frequency to prevent broadcast 
stations from breaking through and 
causing interference. It may be a slug- 
tuned broadcast antenna coil or an 
adjustable rf choke with a range of 
around 60 to 120 ^h. Its tuning capaci- 
tor may be a trimmer instead of a 
fixed unit. 

With the 38-mc oscillator, signals 
between 38,550 and 39,600 kc can be 
received by tuning the receiver from 
550 to 1600 kc and signals between 
36,400 and 37,450 can be heard when 
tuning the receiver from 1600 to 550 
kc. For fixed-frequency operation in 
these ranges, the tuning capacitors 
across L3 and L4 should be peaked to 
the desired frequency and the converter 



output transformer replaced by a 
broadcast antenna coil peaked to the 
converter's output frequency. 

For continuous tuning in these 
ranges, the tuning capacitors across 
L3 and L4 should be ganged and fitted 
with a calibrated dial for peaking. The 
converter output transformer will have 
to be replaced with a self- re son ant out- 
put circuit. You can use a J. W. Miller 
type 472-UA antenna coil or a 2.5-mh 
rf choke and use capacitance coupling 
from the mixer plate to the 39-mc con- 
tact of Sl-b. 

Regardless of the type of operation, 
the oscillator tuning slug and trimmer 
capacitor must be adjusted for mini- 
mum current on a 10-ma meter inserted 
between the 4,700-ohm resistor and the 
junction of L5 and the .OOl-^f bypass 
capacitor. Use a grid-dip meter to make 
sure that L5 is tuned to the crystal fre- 
quency. 

TV HEADPHONE ADAPTER 

One of our household has defective 
heaiing. Even when using a hearing 
aid, he operates radio and TV sets at 
a level that is much too high for others. 
How can headphones be connected to 
the output of the receiver so they can 
be used alone or with the speaker. What 
type of phones are best for this applica- 
tion?— D. M., Bronx, N. Y. 

Here is a simple switching circuit 
that can be used with any receiver. 
Headphones with impedance in the 
range of 6 to 75 ohms are recommended. 



( Continued) 

Phones and adapters are available as 
easy-to-install kits that range from 
around $3.50 to $15, depending on the 
type and quality of the phones. A light- 




weight hearing-aid type of phone would 
probably be more comfortable when 
worn for hours at a time. 

TONE AND VOLUME 
CONTROLS 

Please print the circuit of a volume 
and tone control unit that I can insert 
in the line between my phonograph pre- 
amplifier and the input to a power 
amplifier. The output of the preampli- 
fier is nearly 5 volts and the amplifier 
requires an input of only about 0.75 
volt for full output. Vd like to use 
500,000-ohm controls if possible and 
would like to be able to boost and cut 
the treble and bass. — R. E. D. t Durham, 
N. C. 

This circuit can be used as a remote- 
control panel for your audio system. 
The input and output leads should be 
shielded. If the connecting cables are 
long, insert a 1 -megohm resistor in 







M«< Qfr.-ir -M'"^ 








1956 




IP 

j 




RADIO 
DIAGRAMS 












Urn 










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135 



Supreme Puhlicationgl 

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QUESTION BOX 



(Continued) 



series with the output terminal of the 
preamp and another between the 0.1 -pf 
capacitor and the output terminal of 
the control unit to minimize high-fre- 
quency losses due to the cable capaci- 
tance. 




The losses are rather high in this 
tone-control circuit so it may be neces- 
sary to add another stage of amplifi- 
cation to the preamp or main amplifier 
to compensate. A 6J5, half of a 6SN7- 
GT or any similar tube will provide 
enough gain. 

PHONO MOTOR CLICK 
FILTER 

There is an annoying click in my 
amplifier each time that the phono 
motor is turned on or off. Is there any 
way to eliminate or reduce this click? 
— J. M. F., West Islip, N. Y. 

A click filter can consist of a resistor 
and capacitor in series across the 
switch contacts. The capacitor may 
vary from about .02 to 0.1 /*f and the 
resistor may be any convenient value 
between 50 and 100 ohms. end 



®f)trtp=jftbe |9ear£ £lgo 

In Gernsback Publications 



HUGO GERNSBACK, Founder 

Modern Electric - 1908 

Wireless Association of America 1908 

Electrical Experimenter 1 9 1 3 

Radio News 1919 

Science &. Invention 1920 

Television _ 1927 

Radio-Craft ...„_ 1929 

Short-wave Craft 1930 

Television News 1931 



Some larger libraries still have copies of ELECTRICAL 
EXPERIMENTER on file for interested readers. 



In May 1922 Science and Invention 
(formerly Electrical Experimenter) 

The Radio Explorers, by Robert R. 
Pa rker. 

Radiophoning from Ship to Shore. 
Thomas A. Edison Has Become a 

"Radio Fan." 
Dancing to Radio Music on the Ocean. 
Chicago Police Adopt Radiophone. 
What Caused the Signals?, by John G. 

Merne. 
Radio on Aircraft. 

Continuous Radio Recorder, by Arthur 
H. Lynch. 

Simplest Radiophone Receiver (Second 
Prize), by H. L. Jones. 

Radio Receiver in Fountain Pen. 

Radio Constructor Hints, by H. Win- 
field Secor. 

Radio for the Beginner, by Armstrong 
Perry. 



136 



RADIO-ELECTRONICS 



www.americanradiohistorv.com 



radio-electronic 

Circuits 




with the new model HT-30 
Transmitter I Exciter 

HALLICRAFTERS RAISES THE 
STANDARDS OF 
SSB TRANSMISSION 



SYNCING BAR 

Many bar and dot generators used 
for TV linearity and convergence tests 
have no provision for synchronization. 
This usually results in a very critical 
horizontal frequency setting to obtain 
stationary vertical bars or dots. A 



GENERATOR 

bar generator BG-1. Adding the capac- 
itors to the circuit allows a small signal , 
from both the horizontal and vertical 
deflection circuits of the receiver to be 
fed into the generator, synchronizing 
the bars or dots to the receiver fre- I 











1 MEG 


.002 < 


► K) MEG 



II7VAC 



20^ 



150V 



3|g 



6.3V TO HTR 



minor modification of the generator 
will give excellent synchronization so 
that the receiver checks can be made 
without having to reset the horizontal 
hold control continuously. 

This modification is shown in heavy 
lines on the diagram for the Heathkit 



quencies. Tne horizontal sync lead 
need not be connected directly to the 
horizontal deflection circuit. An insu- 
lated wire laid loosely near the hori- j 
zontal output tube of the receiver , 
usually will pick up a sufficient signal 
for synchronization. 

This modification will work very well 
for other generators; however, different 
capacitors may be necessary. When the 
sync leads are connected directly to the 
deflection circuits, be sure that the [ 
voltage rating of the capacitors is 
sufficient to prevent breakdown by the 
high-voltage pulses which can be as 
high as 2,000 volts.— Henry A. Kampf 



GROUNDED-GRID MODULATOR 



Sometimes a simple wide-band modu- 
lator is needed for a signal generator 
or a low-powered transmitter. A 
grounded-grid amplifier may be easily 
converted into a high-frequency modu- 
lator that handles frequencies ranging 
from near dc to high in the video 



for the carrier frequency by the series- 
tuned trap. 

Fig. 2 shows a similar arrangement 
using a cathode follower driver direct- 
coupled to the grounded-grid modulator. 
In all cases, L and C are selected to 
tune to the rf carrier. — /. F. Barditch 



MODULATED OUTPUT 



I/2I2AT7 




MODULATION INPUT 



range. Although the circuit in Fig. 1 
is not widely used, it will give satis- 
factory results. The grid is grounded 




~ Fit.2 



NOVEL VHF ANTENNA 



The tri-delta (three-element delta- 
matched) 2-meter parasitic array is 
described here. See Fig. 1. It has a 
gain of nearly 8 db and may be fed 
either with 300-ohm ribbon or 50-75- 
ohm coax. Designed for portable opera- 

M AY, 19 5 6 



tion with the Gonset Communicator II, 
it is used for reception and transmis- 
sion of vertically polarized signals but 
can be turned on its side for horizontal 
polarization. 

The delta provides an essentially flat 



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HEADPHONE JACK. 
10 METER TUNING CONTROL. 
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hallicrafters 



CHICAGO 24, ILLINOIS 



137 



www.americanradiohistorv.com 




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RADIO-ELECTRONIC CIRCUITS (Continued) 

mate h betwee n the ra d i ator and the 
300-ohm input terminals and a good 
means of bringing the lead-in out of 
the field around the active elements. 
The connection between the delta and 
the 300-ohm ribbon is made at an insu- 



ALUMINUM 3/8"O0 




lating block constructed as in Fig. 2. 
The ribbon is clamped to the block to 
ease the strain on the connections. 

The delta section is No. 10 tinned 
bus bar fanned out approximately 7 
inches each side of the radiator's cen- 



M0UNTING HOLE 




TEXTOLfTT. OR SIMILAR MATERIAL 



ter. Adjustable, it is fastened to the 
radiator with sliders from 10-watt 
adjustable resistors. For best results, 
the sliders should be adjusted for the 
best standing-wave ratio. 

A length of 300-ohm ribbon is used 



CENTER CONDUCTORS TO 300/v LINE 



L- A/4 




138 



-SHIELDS TIED TOGETHER 

CENTER CONDUCTORS TIED TOGETrCR 

H^- TO SOa OR 75a COAX 

^COAX CONNECTOR 

Fij.3 

to maintain a balanced line close to the 
antenna. When coax is used, the impe- 
dances are matched with a balun (bal- 
anced-to-unbalanced) transformer con- 
structed from RG/62-U 93-ohm coax 
as in Fig. 3. This type of cable tends 
to flatten out the overall standing- wave 
ratio somewhat more than most others. 

RADIO-ELECTRONICS 



www.americanradiohistorv.com 




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RADIO-ELECTRONIC CIRCUITS (Continued) 
(An antenna is matched to a trans- 
mission line when its input impedance 
equals the effective characteristic im- 
pedance of the transmission line. When 
the two are matched the voltage stand- 
ing-wave ratio is unity. Thus, the 
match between antenna and transmis- 
sion line can be determined by either 
measuring the SWR or the antenna's 
input impedance. Simple standing-wave 
and antenna impedance bridges are 
described in detail in recent editions 
of The Radio Amateur* s Handbook. 
— Editor) 

Some additional gain can be obtained 
by using additional directors, each 
being cut about 5 c /c shorter than the 
nearest one between it and the radiator. 
However, when the directivity improve- 
ment is balanced against the increase 
in overall size, a three-element unit is 
about right for portable use. — C. O. 
Field 

( The resonant frequency of this 
antenna is approximately 145.8 mc. For 
other frequencies, scale the dimensions 
up or down in proportion to the ratio 
of the frequencies. — Editor) 

6AS7-G's IN POWER SUPPLIES 

The 6AS7-G is an excellent regulator 
tube for power supplies whose output 
current is around 200 ma but has one 
serious drawback — there are variations 
in the triode sections of the tube. These 
sections are usually connected in paral- 
lel and controlled by a single biasing 
voltage as in Fig. 1. For a given con- 
trol voltage the variations cause an 
uneven distribution of the currents in 
the two sections of the tube. This is 
not serious at low-current levels, but it 



6AS7-G 




is when current is high. If one triode 
draws considerable more current than 
the others, it will overheat. As it over- 
heats, it tends to draw more current. 
This "regeneration" continues until the 
tube is destroyed. 

Some attempts have been made to 
reduce this effect by inserting cathode 
resistors in the regulator circuit to 
develop cathode degeneration, but this 
is not too effective as the cathode degen- 
eration is negligible compared to the 
thermal "regeneration. " 

Tube selection at the price of the 
tube is prohibitive for experimenters 
and expensive for manufacturers of 
equipment using the tube. Tubes are 
plugged in and, if one section gets red 



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RADIO-ELECTRONIC CIRCUITS (Continued) 

hot, it is unbalanced and the tube must 
be replaced. Fortunately, only a small 
percentage of them are prohibitively 
unbalanced. 

When installing a 6AS7-G in a regu- 
lated power supply, the triode sections 
may be adjusted for optimum perform- 
ance by using the simple circuit shown 
in Fig. 2. A potentiometer is installed 



REGULATOR 

"| 6AS7-G 




Fij.2 

and the control voltage adjusted to the 
grids of the tube until the current bal- 
ances. This is done at about two thirds 
of the maximum current for which the 
supply is designed. Once set, the tubes 
remain fairly well balanced throughout 
the current range if the maximum plate 
voltage is not exceeded. If the supply 
is to be used in a fixed load circuit, the 
adjustment is made at the operating- 
load. 

My supply has a single tube. If more 
than one tube is required, it is not dif- 
ficult to modify the circuit. The supply 
is adjusted as follows: 

1. Set the balance control so its arm 
is at the plate of the control tube. 

2. Connect an appropriate load to 
the output of the supply. 

3. Measure the voltage across the 
cathode resistors of the triodes to find 
the section delivering the least current. 

4. Turn off the power supply and 
then throw the d.p.d.t. switch to the 
position that connects the grid of that 
section to the arm of the balance con- 
trol. (The power supply should be 
turned off when throwing the selector 
switch to avoid damaging it as the 
grids are momentarily opened.) 

5. Connect a voltmeter across the 
cathodes of the triode sections and 
adjust the balance control until the 
cathode voltages (and therefore the 
currents) are equal. 

The values shown have worked well 
for me, but variations may be made 
to suit the individual case. The cathodes 
of the triodes may be brought through 
the chassis with pin jacks for future 
adjustments. The balance control should 
be a screwdriver-adjusted type and 
should be placed behind the front panel. 
— R. P. Jamison end 



RADIO-ELECTRONICS 



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Business 




Merchandising and Production 

RCA Tube Div., Harrison, N. J., is 
sponsoring- an all-out sales promotion 
program on its batteries. The plan in- 
cludes extended payment terms, buying 
benefits and technical selling tools. 
Counter merchandisers, window dis- 
plays, advertising mats, etc. were pre- 
pared for dealers and distributors. 

Winegard Co., Burlington, Iowa, is 
planning a trade and consumer promo- 
tional campaign on its TV antenna line. 




The photo shows John R. Winegard 
(right), president of Winegard, dis- 
cussing the campaign with Burton 
Browne, head of the company's ad- 
vertising agency. 

Service Instruments Co., Addison, 111., 
designed a four-color display board for 
its small service units. The board is 
equipped with easels and hooks so that 
it may be hung or set on a counter. 

Brach Manufacturing Co. t Newark, 
N. J., was featured recently on Bob 
Considine's "Cavalcade of Progress" TV 
show over WABD channel 5, New York. 
Ira Kamen, Brach's vice president in 
charge of electronic research, and 
Jerome Berger, plant manager, were 
interviewed and several of the com- 
pany's new products were introduced. 

National Radio Week will be cele- 
brated May 13 to 19. It is sponsored 
by the National Association of Radio 
& TV Broadcasters, the Radio Adver- 
tising Bureau, RET MA and the Na- 
tional Appliance & Radio-TV Dealers 
Association. 

Production and Sales 

RET MA reported that a record 7,421,- 
978 TV sets were shipped to dealers 
during 1955. The association also re- 
ported that manufacturers' sales of 
transistors reached a total of 3,646,802 
units last year, nearly three times the 
previous year's total. 

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No. 56. By Norman Crowhurst 
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141 



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BUSINESS 



(Continued) 



National Airlines Depends on Electro 

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142 



Association, New York, reports that 
I about 20% more recorders were sold 
| in 1955 than 1954. Total production 
I for 1955 was estimated at 360,000 units. 
RETMA reported that 43,099,796 TV 
sets had been shipped to dealers during 
the past 10 years. It also reported TV 
picture-tube sales of 892,385 units for 
January, 1956, compared with 866,956 
for January, 1955. Comparative sales 
of receiving tubes were 40,140,000 in 
January, 1956, as against 37,951,000 in 
1955. 

Mergers 

Textron American Inc.. Boston, 
Mass., acquired all outstanding stock 
of General Cement Manufacturing Co., 
Rockford, 111., manufacturer of TV an- 
tennas and technical aids. Stanley B. 
Valiulis, president of General Cement, 
will head the new Textron division. 

P. R. Mallory & Co., Indianapolis, 
Ind., acquired General Dry Batteries, 
Inc., Cleveland, Ohio, which it will oper- 
ate as a division, subject to stockhold- 
ers* approval. 

Astron Corp., East Newark, N. J., 
bought all the outstanding stock of 
Skottie Electronic Corp., Peckville, Pa. t 
including buildings and production fa- 
cilities. Skottie manufactures ceramic 
capacitors. 

New Plants and Expansions 

Sprague Electric Co., North Adams, 
Mass., is beginning construction on a 
new 20,000-square-foot plant in Con- 
cord, N. H., for the manufacture of 
surface-barrier transistors. 

Merit Coil & Transformer Corp., 
Chicago, opened a new warehouse in 
San Francisco to improve service to its 
West Coast distributors. 

International Rectifier Corp. relocated 
its New York office in larger quarters 
at 132 East 70th St. 

Allen B. Du Mont Labs transferred 
its Missile Engineering Dept. from 
Clifton, N. J., to Los Angeles. 

Westinghouse has begun work on a 
new 120,000-square-foot electronic-tube 
warehouse in Elmira, N. Y. 

Business Briefs 

. . 1956 High-Fidelity Show and Music 
Festival will be held in the Palmer 
House in Chicago Nov. 2-5. The show 
management announces that all display 
rooms will be air-conditioned and ele- 
vator service will be improved. 
. . . Westlab Electronics, Yonkers, 
N. Y., formerly a partnership, has been 
incorporated. Officers include Ira B. 
Perelle, president; Lois A. Brook, vice 
president, and Louis Petta, secretary. 
. . . Ray-O-Vac Co., Madison, Wis., 
has adopted the NEDA numbering sys- 
tem for its complete line of radio 
batteries. 

Correction 

In the March issue an item stated 
that Tescon TV Products Co., Inc. was 
imprinting its distributors' names on 
its antenna cartridges. This should 
have read on its antenna cartons, end 

RADIO-ELECTRONICS 



www.americanradiohistorv.com 



.people 




Dr. Thomas T. 
Goldsmith, Jr., vice 
president research, 
of Allen B. Du 
Mont Labs., Clif- 
ton, N. J., was 
named vice presi- 
dent and general 
manager of the 
Government and Research Div. in a 
move to consolidate all government 
manufacturing, engineering and sales 
operations into one division. He will 
continue to direct the company's Re- 
search Div. 

Merle W.Kremer 

was appointed as- 
sistant general 
manager of the 
Sylvania Parts 
Div., Warren, Pa. 
He will continue 
his present duties 
as general manu- 
facturing ! manager, with plants at 
Cleveland and Nelsonville, Ohio, as 
well as at Warren. 

Harold F. Cook (left), advertising 
manager of Tung-Sol Electric, Inc., 
Newark, N. J., was appointed to the 
newly created post of director of ad- 






vertising and market research. Robert 
M. Andrews (right), former assistant 
advertising manager, was named man- 
ager of advertising and sales promo- 
tion for electronic products. 

Edward G. Hazeltine was appointed 
manager of advertising and sales pro- 
motion for automotive products and 
will continue as manager of TBA sales. 
Gerald A. Morgan, former market 
analyst, was named manager of market 
research. 

John D. McNa- 
mara joined Wes- 
ton Electrical In- 
strument Corp., 
Newark, N. J., as 
field sales mana- 
ger. He was for- 
merly with Beck- 
J^^^^^f man Instruments 

.ij^^^^P^ l nc . f as that com- 

pany's industrial sales manager. 

MAY, 1956 



from the VOICE OF AUTHORITY IN SWEEPS . . . 

SPOT and FIX 
TV FAULTS fAsn 

FREE RAM BOOK SHOWS HOW! 

Typical latest field-proven servicing data 



W'T* 



RAM Electronics Sales Co. 
Irvington, New York 

Send me FREE 1956 RAM "PIX-A-FAULTS" 
BOOK. 

Name _ 

F Irm , — - 

Street — ___ — 

City. Zone State I 



i you'// find in your RAM book: ^ 




9< I 



FAULT: "Ringing." 

CAUSE: Incorrect value of balancing 

R-C network across one-half of H. 

Yoke winding. 
(A): H. Yoke current wave-form. 

Obtained by connecting scope 

across 10-ohm resistor inserted 

Id series. 



FAULT: Picture compression and 

stretching. 
CAUSE: Capacitance value of boost 

capacitor (connected to linearity 

coil) too low. 
(B): H. Yoke current wave-form. 

Leaky boost capacitor could cause 

similar effect. 



FAULT: Picture stretching at left 
and compression at right. 

CAUSE 0 02 mf boost capacitor 
(connected to linearity coil) used 
instead of 0.1 mf capacitor. 

(0): H. Yoke current wave-form. 



For over 10 years, RAM has specialized and pioneered in sweeps exclu- 
sively RAM designs them, makes them, counsels TV set manufacturers 
on them, field-services them, educates Servicemen on them — leads the 
industry. 

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in the RAM Manual. In manufacturing know-how and field experience, 
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Export Oept: Dage Corp., 219 E. 44 St., New York, N. Y. 




6-VOLT BATTERY SOLDERING IRON AND WELDER 



U.S. Army release. Brand 
New — Never Used. Fully 
Guaranteed. This soldering 



iron can be used to solder «*-^sr 
or weld when connected to "V 
any six-volt storage battery. 
Uses approximately 200 to 300 \, 



watts. The high intensity arc 
created between the metal to 
be soldered and the carbon 
electrode (carbons supplied 
free with iron) can be used to 
heat tin or aluminum solder. Suitable also for 
light brazing and spot welding. Arc can be used 



APPROX 

200 TO 
300 WATTS 




ITEM NO. ._ 
UNUSUAL BUY 



for melting metals, cutting 
holes and soldering seams in 
chassis. Also useful for ana- 
lyzing metals and minerals. 

Battery soldering iron out- 
fit includes 2 carbons, 3 
heavy duty spring clips, 2 
pieces 5 ft. heavy duty wire 
cable. (Battery not included.) 
Ideal for use where current is 
not available. _ _ 

Ship wt. 4 lbs. $1 b 9§ 

(P.P. & Hdlg. ChOs. 50c) 



VARIABLE SPEED UNIVERSAL MOTOR 

FOR 110 VOLTS, A.C. OR D.C. 
Used, but in excellent condition. 
Special lever control permits varia- 
ble speeds up to 3000 r.P.m.. \U" 
* shaft extends from both sides of 
motor. Measures 7V 2 x 3!4" <!iam. overall ShP. Wt. 
6 3 / 4 lbs. 

$2.45 

p"'p'.''&~H'dTg. Chgs. 75c 



Your Price.. 



AMAZING BLACK LIGHT 



250-watt ultra-violet light 
source. Makes fluorescent 
articles glow in the dark. 
Fits any lamp socket. For 
experimenting, entertaining, 
unusual lighting effects. 
Ship. wt. 2 lbs. 
ITEM NO. 87 

{P. P. & Hdlg. Chqs. 35e) 



$2.45 




POWERFUL ALL PURPOSE MOTOR 

Sturdy shaded pole A.C. induc- 
tion motor. 15 watts, 3000 rpm. 
3"x2"xl y A "\ 4 mounting studs; 
V 8 " shaft, 3/16" diameter; 110- 
120 volts, 50-60 cycles. A.C. only. 
ITEM NO. 147 CO A C 

UNUSUAL BUY 

(P.P. & Hdlg. Chgs. 3Sc) 




(P.P. & Hdlg. 
Chgs. $1.25) 



WATTHOUR METER 

Leading makes — reconditioned. 
Ideal for trailer parks. 100-110 
volts, 60 cycles, 2-wire A.C. 5 
amp. Heavy metal case Sfa" x 
x 5". Easy to install. Ship, 
wt. 14 lbs. 
ITEM NO. 33 



$4.50 



BLAK-RAY SELF-FILTERING 

ULTRA-VIOLET LAMP 

BLAK-RAY 4-watt lamp, 
model X-4. with U-V tube. 
Lamp has a wave-length of 
3654 to 4O00 angstrom units. 
Some of the substances made 
to fluoresce are certain 
woods, oils, minerals, milk- 
stone, cloth, paints, plastics, 
yarn, drugs, crayons, etc. 
Self-filtering and harmless, 
equipped with aluminum reflector. 110 volt 50-60 
cycle A.C. 2000 to 3000 hours of service. Approved 
by U/iderwriters has a bu'lt-in transfori 
ITEM NO. 125 




(Shp Chgs. 80c) 



$16.75 




HUDSON SPECIALTIES CO. 
25 West Broadway, Dept. RE 5-56 
New York 7, N. Y. 



N. 

I am enclosing full remittance for items circled 
below. (Be sure to include shipping chai*ees.) 



250 POWER TELESCOPE LENS KIT 

Make your own high powered 6 ft. telescope! 
Kit contains 2" diam., 75" focal length, ground 
and polished objective lens 
and necessary eye pieces. 
Magnifies 50x to 250x. Full 
instructions. 

ITEM NO. 123 CO QC 

(Shp. Chas. 10c) 



Ship balance C.O.D. 

order ss.oo. 



OR. my deposit of : 

MINIMUM C.O.D. 
C.O.D. ORDERS ACCEPTED ONLY WITH 20<>,o DE- 
POSIT. INCLUDE SHIPPING CHARGES. 
87 147 33 126 123 125 127 




Please Print Clearly 



..Zone State.. 



143 



www.americanradiohistorv.com 



DON'T just 

SIT UMCIMS 

j Ask For Sprague By 

Catalog Number 

Know what you're getting . . . 
get exactly what you want. 
Don't be vague . . . insist on 

i Sprague. Use complete radio- 
TV service catalog C-610. 
Write Sprague Products Com- 

[' Pany, 81 Marshall Street, 
North Adams, Massachusetts. 

SPRAGUE 

WORID'S LARGEST 
CAPACITOR MANUFACTURER 



Make sure . . . 

You get every issue of 

RADIO-ELECTRONICS 

(The Annual Index in the De- 
cember issue makes it easy to 
find what you want in every 
issue at any time.) 

Subscribe NOW and SAVE 

One Year $3.50 

Two Years $6.00 
Three Years $8.00 

Canada same as U. S. 
Extra postage per year: 

d Pan-America, 50c 

□ all other foreign, $1.00 



TAPE RECORDERS 



Tapes — Accessories 

Nationally Advertised Brands 

UNUSUAL VALUES 

Send for Free Catalog 

DRESSNER 

69-02 RE 174 St. 
Flushing 65, N.Y. 




REPAIR TV PICTURE TUBES 
WITHOUT COST OR EQUIPMENT 

Give new life to old or defective tubes. Remove shorts. 
Restore emission and brightness. Servicemen rio it- — 
you can. tool Montli* of extra service. Results com- 
pare with most expensive instruments. Save money 
by fixing your own tutx-s. Earn extra motley fixing 
tubes for others. Be prepared, earn lame profits re- 
pairing expensive color picture tubes, beam this easy, 
tried and tested method now and cash In! Order now I 

SPECIAL OFFER complete instructions $1 

TELEPARTS CO. 

172 Narragcmsett St. Edgewood 5, R.I. 



PEOPLE (Continued) 

Mai Parks, Jr. 

joined Howard W. 
Sams & Co., Indi- 
anapolis, Ind., in 
an executive ca- 
pacity. He had been 
publisher of Parts 
Jobber Magazine. 

Louis H. Niemann (left) was named 
equipment sales manager at CBS-Hy- 
tron. He was formerly Eastern district 






sales manager. Lee Ballengee, Jr., 
(right) formerly with General Instru- 
ment Corp., suceeds him as Eastern 
district sales man- 
ager. Herbert L. 
Reichert, formerly 
Central district 
manager for CBS- 
Hytron, was ap- 
pointed Midwest 
regional manager 
for CBS-Hytron Sales Corp, with head- 
quarters in Chicago. 

W. Ropp Triplett, general manager 
of Triplett Electrical Instrument Co., 
Bluffton, Ohio, was named president 
of the company. Ray L. Triplett, found- 
er and president, becomes chairman of 
the board. The photo shows W. Ropp 
Triplett (center), one of the two sons 
of the founder, being congratulated 
by Norman Triplett, vice president and 
sales manager, while M. Morris Trip- 
lett, the other son of the founder, and 
vice president, engineering, looks on. 




Beg Pardon 

In the April issue, the photos of 
Ken Hathaway, who was elected treas- 
urer of the Association of Electronic 
Parts and Equipment Manufacturers, 
and Russel Schlegel, who joined Weston 
Electrical Instrument Corp. as manager 
of Industrial Product Sales, were trans- 
posed. 

Obituary 

Robert Robins, a public relations 
counsel and radio pioneer, at his home 
in Forest Hills, N. Y. He was at one 
time president of Cath-Ray Electronics 
Corp. and the Duovac Radio Tube Corp. 

Personnel Notes 

. . . James H. Carmine, retired as pres- 
ident of Philco Corp., but will continue 
as a member of its board and Finance 
Committee. He is to be succeeded by 
James M. Skinner, Jr., director and 



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144 



RADIO-ELECTRONICS 



www.americanradiohistorv.com 



PEOPLE 



( Continued ) 



vice president and general manager 
of the Television Div., pending approval 
by stockholders. 

. . . George J. Parker, former presi- 
dent of the Daystrom Instrument Div., 
was appointed vice president of Day- 
strom Inc. in charge of its Washington 
office. Walter W. Slocum, vice president 
of operations for Daystrom Inc., will 
assume responsibility for the operation 
of the Instrument Div. 
. . . Andrews Ferguson was placed in 
charge of New England distributor 
sales for Sprague Products Co., North 
Adams, Mass. He was formerly field 
representative for the company. Albert 
Coumont, who had been service co- 
ordinator and staff assistant to the 
RETMA Parts Div., joined the Sprague 
Electric Co. Distributor Sales Div. 
. . . Arthur I. Rabb, advertising and 
sales promotion manager of United 
Catalog Publishers, Inc., New York, 
was promoted to general manager. 
George Siegel, former assistant adver- 
tising manager, succeeds him. Herman 
Holstein was named editor of Radio- 
Electronic Master. Other appointments 
include: George M. Kerner, manufactur- 
er liaison, and Robert J. Males, admin- 
istrative assistant. 

. . . Harold A. DeMooy was appointed 
manager of manufacturing for RCA 
receiving tube activities at Harrison, 
and Woodbridge, N. J., Indianapolis, 
Ind., and Cincinnati, Ohio. He had been 
in charge of the tube plant in Cincin- 
nati. John B. Farese was named man- 
ager, personnel, for the division. He 
had been manager of manufacturing 
for the concern . . . William L. Eschwei, 
manager of radio assembly inspection 
and test at the Clifton, N. J. plant of 
Federal Telephone & Radio Co., was 
named plant manager of the Pacific Div, 
Joseph F. Rapone, superintendent of 
radio assembly, succeeds him. 
. . . Peter L. Jensen, chairman of the 
board of Jensen Industries, and Edwin 
S. Pridham, former vice president of 
Magnavox, were named honorary mem- 
bers of the Audio Engineering Society 
for their pioneer work on the electro- 
dynamic loudspeaker in 1915. 
. . . Avery Fisher, Fisher Radio Corp., 
was elected chairman of the Board of 
Directors of the Institute of High Fi- 
delity Manufacturers. 
. . . Robert L. Ashley, with the com- 
pany since 1952, was appointed sales 
manager for germanium and silicon 
products by Radio Receptor Co., Inc., 
Brooklyn, N. Y. 

. . . Harry A. McDonald, investment 
counselor, was elected to the Board of 
Directors of Sonotone Corp., Elmsford, 
N. Y. 

. . . John M. Palmer was named man- 
ager of the new Spring City, Pa., plant 
of the Lansdale Tube Co., a division of 
Philco. He had been manager of receiv- 
ing and cathode-ray tube operations. 
. . . Herbert C. Guterman, who has had 
wide industrial operating experience 
in the electronics field, was elected 
chairman of the board of National Co., 
Maiden, Mass. end 



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Please Print 



CITY - STATE... 



MAY, 1956 



145 



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G-E BROCHURE 

An 8-page brochure ECG-95 contains 
condensed specification and rating data 
on transistors and rectifiers, critical 
parameters for absolute maximum rat- 
ings and design center ratings for G-E 
n-p-n and p-n-p transistors; critical 
specifications for germanium rectifiers 
including basic rectifier units; high- 
temperature, magnetic amplifier and 5- 
amp power rectifiers; rectifier stacks, 
including medium-power, in various 
applications. 

Brochure or individual specification 
sheets from Semiconductor Products 
Section, General Electric Co., Elec- 
tronics Park f Syracuse, N. Y. 

BUD CATALOG 

Catalog No. 156 describes sheet-metal 
products and electronic components. In 
addition, special fabrication facilities 
are outlined. Complete sizing informa- 
tion is given on each product and 
suggestions for uses and applications 
are also included. 

Bud Radio, Inc., Dept. Cs, 2118 E. 
55 St., Cleveland 3, Ohio. 

SPEAKER SYSTEMS 

A comprehensive Guide to High- 
Fidelity Loudspeaker Systems stresses 
the importance of the loudspeaker in 
any home music center and provides 
basic facts on how to choose a loud- 
speaker system. It gives details about 
integrated, separate and completely 
assemb'ed two-, three- and four-way 
systems as well as acoustically designed, 
furniture-styled enclosures to suit indi- 
vidual budgets, space, decor and musical 
tastes. It also includes information 
about Electro- Voice do-it-yourself high- 
fidelity enclosure kits and the avail- 
ability of individual speaker system 
components. 

Electro-Voice, Inc., Buchanan, Mich., 
25c. 

SELENIUM RECTIFIERS 

Form HTl describes the new Sarkes 
Tarzian line of selenium rectifiers de- 
signed to operate at full voltage and 
current without derating at tempera- 
tures as high as 150°C. 

Sarkes Tarzian Inc., Rectifier Div., 
U15 No. College Ave., Blooming ton, Ind. 

AMPLIFIERS 

RCA's Catalogs S3027, S3026 and 
S3023 give data on applications, de- 
scriptions, specifications and accessories 
of 30-watt amplifiers MI-12154, type 
SA-34A, MI-12155, type SA-32A and 
15-watt sound amplifier MI-12156, type 
SA-15A. 



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WANT BACK ISSUES? 

Back numbers of most issues of 
RADIO-ELECTRONICS are available upon 
request 

This year's issues 35c 
Last year's issues 40c 
Previous year 45c, etc. 
All January TV issues 50c 

RADIO-ELECTRONICS 



154 West 14 St. 



New York 11, N, Y. 



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146 



Every kit complete with step-l>y-stop fully illus- 
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Write today for FREE catalogue and name of 
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duality-Electronics Dept. e-4 

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RADIO-ELECTRONICS 



www.americanradiohistorv.com 



TECHNICAL LITERATURE 

Radio Corp. of America, Sound Prod- 
ucts, Camden, N. J. 

NEEDLE CATALOG 

A 73-page catalog includes a car- 
tridge-to-needle listing, illustrated car- 
tridge index, illustrated needle listing 
with an index and needle installation 
data. 

Permo, Inc., 6415 Ravenswood Ave., 
Chicago 26, III. 

MAGNETS 

Cast, sintered, ductile and formed 
permanent magnet materials are dis- 
cussed in manual No. 5, Permanent 
Magnets Materials and Their Selection. 
A selector type chart summarizes the 
magnetic characteristics, application 
and design factors, material charac- 
teristics, manufacturing methods and 
shape limitations of each. 

Other sections of the manual discuss 
the hysteresis loop and demagnetization 
curve, temperature limitations, direc- 
tional properties, incremental perme- 
ability, hysteresis loss, etc. 

A glossary of magnetic terms, listing 
of magnetic symbols and graphic illus- 
tration of material characteristics are 
also included. 

Indiana Steel Products Co., Val- 
paraiso, Ind. Use your letterhead. 

BENCH TOOLS 

A 40-page catalog describes insulated 
and noninsulated screwdrivers, nut 
drivers, pliers, service tool kits, align- 



ment and specialty tools, etc. Heavily 
illustrated with photos, charts and 
tables. 

Vaco Products Co., 317 E. Ontario 
St., Chicago 11, III. Requests must be 
on letterheads. 

INSTRUMENT TYPE SWITCHES 

An 8-page Catalog 17-SE describes 
instrument type switches. Illustrations, 
complete code system outline and 
specifications are included in the data. 

Cinema Engineering Co., Acrovox 
Div., 1100 Chestnut St., Bur bank, Calif. 



Any or all of these catalogs, bulletins, or 
periodicals are available to you on requesl 
direct to the manufacturers, whose addresses are 
listed at the end of each item. Use your letter- 
head—do not use postcards. To facilitate iden- 
tification, mention the issue and page of RADIO- 
ELECTRON ICS on which the item appears, 
UNLESS OTHERWISE STATED, ALL ITEMS ARE 
GRATIS. ALL LITERATURE OFFERS ARE VOID 
AFTER SIX MONTHS. 



MULLARD AUDIO TUBES 

This leaflet describes the EF86, 
EEC83, EL84 and EL34 tubes designed 
for audio equipment. The electrical 
characteristics of each are given to- 
gether with tables on typical operating 
conditions. In addition, preliminary 
technical data are given for the EZ81 
and GZ34 full-wave rectifiers. 

International Electronics Corp., Si 
Spring St., New York 12, N. Y. 



(Continued) 

PAPER CAPACITORS 

Catalog 155 describes paper capac- 
itors for ac and dc applications. Data 
on mineral-oil-impregnated paper-die- 
lectric capacitors in a variety of con- 
tainers, synthetic- oil- impregnated 
paper-dielectric capacitors, etc. are in- 
cluded. Charts and diagrams also given. 

Plastic Capacitors, Inc., 2511 W. 
Moffat St., Chicago 47, III. 

ELECTRONIC EQUIPMENT 

Newark's 1956 catalog devotes more 
than 20% of their catalog to audio and 
high-fidelity equipment, as well as a 
large line of radio and TV repair equip- 
ment, components, radio hardware, etc. 

Newark Electric Co., 223 W. Madison 
St., Chicago 6, III. 

OUTPUT TRANSFORMERS 

A 6-page folder contains complete 
data and three schematics of Dynaco 
output transformers. A chart on color 
coding of transformer leads is also in- 
cluded. 

Dgna Co., 5142 Master St., Philadel- 
phia 31, Pa. 

AUDIO EQUIPMENT 

Langevin's catalog describes trans- 
formers, reactors, amplifiers, power 
supplies and special equipment. 

Langevin Mfg. Corp., Subsidiary of 
W. L. Maxson Corp., 47-37 Austell PL, 
Long Island City 1, N. Y. end 



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SEND NO MONEYl Just mail coupon for 7-volume set on 7 days free trial. 
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MAY, 1956 



147 



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THE LONG PLAYING RECORD 
GUIDE, by Warren De Motte. Dell 
Books, 200 F ifth Ave., New York, N. Y. 
50c. 

Even the connoisseur who knows both 
the music and the orchestras would 
have difficulty choosing between 20 
recorded versions of the same work 
assuming he could even manage to hear 
them all. The typical listener who lis- 
tens primarily because he loves music 
and pretends no expertness about it 
is usually completely at a loss. Warren 
De Motte in this inexpensive pocket- 
book offers guidance to both classes of 
listeners and in my view succeeds bet- 
ter than others in more pretentious 
and expensive guides. 

In a work like this the author cannot 
avoid being colored by his personal 
likes and dislikes, tastes, preferences 
and even prejudices. I particularly like 
this work because Mr. De Motte does 
less categorical judging and more 
describing of differences in perform- 
ance, interpretation and recording than 
others. He does mark with an arrow the 
recording which in his view is the 
best of the available lot, but he also 
gives the highlights or deficiencies of 
all versions succinctly but clearly 
enough so those whose taste may differ 
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them in their own choice. 

Judging by the small percentage of 
works I have heard myself, Mr. De 
Motte compiles a very good batting 
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the complete layman does not run 
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fan will also be well served for Mr. 
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The book does not even begin to pre- 
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ings. It concentrates almost entirely 
on those most popular classics of which 
there are several recordings. The 
arrangement is alphabetical by the 
name of the composer. — JM 



145 West 40 Street New York 18, N.Y. 



FUNDAMENTALS OF TELEVISION 
ENGINEERING, bv Glenn M. Glasford. 
McGraw-Hill Book Co., Inc., New York, 
N. Y. 6 x 9 inches, 642 pages. $12.75. 

This text is not for most service 
technicians but is suitable for engineers 
and advanced TV technicians. It covers 
the entire TV field from a theoretical 
viewpoint. Math is used extensively and 
there is considerable material on La- 
place transforms and their applications. 



148 



RADIO-ELECTRONICS 



www.americanradiohistorv.com 



STANLEY ELECTRONICS 




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BOOKS (Continued) 

Color TV is analyzed along with black- 
and-white. 

Among important chapters are those 
on scanning, synchronizing, wideband 
amplifiers and restorers. The transmit- 
ting end of TV is covered in chapters 
which study problems relating to 
cameras, video transmitters and anten- 
nas. — IQ 



tOM», 



GReqory 1.2498 



Get Better Results from 
your V.T.V.M. 

READ — 

Gernsback Library Book No. 57 

Paper cover edition $2.50 

On sale at all better parts 
distributors or write: 

Gernsback Library, Inc. 

154 West 14 St. 
New York 11. N. Y. 



A GUIDE TO GOOD BUSINESS, pre- 
pared bv Merchandising Dept., Sylvania 
Electric Products, 1100 Main St., Buf- 
falo, N. Y. 40 pages. 8V 2 x 11 inches. 

Free from Sylvania Central Adver- 
tising Distribution Dept. 

Published as an aid to present and 
future electronic service dealers, this 
booklet attempts to show the many 
things to be considered in opening and 
operating a radio and television sales 
and service shop. Among the subjects 
covered are original planning, survey- 
ing market conditions, choosing the 
right location, ideas and suggestions 
for window displays and arranging the 
work shop area. 

The text is heavily supplemented with 
photos and drawings. Covering so many 
subjects in so few pages, the book is 
necessarily superficial in its treatment 
of each. However, several references 
are given to more detailed works on 
specific subjects. 

Overall, the booklet is slanted toward 
sales and away from servicing, notice- 
ably lacking in its treatment of test 
equipment and servicing supplies. For 
the prospective service dealer, A Guide 
to Good Business is just exactly that. 
— JK 



PRACTICAL RADIO SERVICING, by 
William Marcus and Alex Levy. Mc- 
Graw-Hill Book Co., Inc., 330 W. 42nd 
St., New York 36, N. Y. 6x9 inches, 
565 pages. $8.50. 

This book should interest professional 
radio men as well as prospective tech- 
nicians for members of the first group 
will want to recommend it to their 
friends in the second. Starting right 
from the beginning, nothing is taken 
for granted. The reader is told how 
to solder, shown how to remove a 
chassis and how to make simple tests. 
As he gains knowledge he proceeds to 
more complicated tests and trouble- 
shooting. 

The more common types of radios are 
discussed here: ac-dc, battery portable, 
phonograph. Diagrams show typical 
placement of components and tubes and | 
where the set adjustments are located. 
Separate treatment is given to the | 
power supply, if strip, audio and con- 
verter. Instruction is given on the use 
of an ohmmeter, multimeter and tube 
tester. 

Valuable features are the assigned 
"jobs." The reader is asked to provide 
himself with an old set for experimental 
work and he is told how to take meas- 
urements and draw schematics. Deliber- 
ate defects may be introduced by the 
experimenter so he may learn to recog- 
nize faults and symptoms through 
experience. — IQ 



SERVICE 
AIDS 

UNIVERSAL 
CHEATER- PATCHCORD 




The AD-60 is supplied in two parts - the 
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Inserting the special cord inta One end of 
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list Me. $2.25 

POCKET UTILITY 
PROBE PR200 



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Rapid position tests for 
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end CATHODE RAY TUBES. Continuity tests can 
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ment. Unlike most series filament and continuity 
testers, the PR-200 Pocket Probe is designed to 
easily fit the serviceman's pocket and tool box. 
The PR-200 prabe is entirely shock-proofed and 
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Complete 
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Signal Tracer 

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Visual Output Meter 

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A true subminiature pocket tester which affords 
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Instruments, compactly mounted 
in sturdy metal case. 



NET 



MAY, 1956 




SALES CO. of N. Y. 

130 LAFAYETTE ST. 
NEW YORK 13, N. Y. 



www.americanradiohistorv.com 




School 
Directory 



wanted career men 



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Train for a career instead of a job. 
Demand for our graduates exceeds supply. 
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RCA INSTITUTES, INC. 

A service of Radio Corporation of America 
350 West 4th St.. New York 14. N. Y. 

OFFERS COURSES IN 
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BOOKS 

THE VTVM. by Rhys Samuel. Gems- 
back Library (No. 57), New York, N. Y. 
5'/ 2 x 8«/ 2 inches, 224 pages, $2.50 

This "workingman's book" is equally 
suitable for beginners because it is 
clearly written and avoids deep theory 
or calculations. It tells all about the 
vtvm and probes, and covers operation, 
use and maintenance. One chapter lists 
possible defects in the vtvm and how to 
correct them. 

The basic idea behind this book is to 
explain the virtues (and also the faults 
— or limitations) of the vtvm — to show 
what you can reasonably expect the 
instrument to do. 

Among the many applications de- 
scribed here are several that are emi- 
nently suited to a vtvm but sometimes 
not known or understood. Tests and 
measurements of impedance, ripple, 
stage gain, transformers are discussed. 
Other topics include scope calibration, 
receiver alignment and high-resistance 
measurements. 

For the sake of completeness, the 
author even describes chores generally 
left for other types of equipment be- 
cause the vtvm is considered too cum- 
bersome or insensitive for the particular 
job. These include transmitter neutral- 
ization, kinescope tube test and band- 
pass curve plotting. 

Useful data are provided in db charts, 
capacitor leakage values and schematics 
of receivers and various types of vtvm 
circuits. 



INTRODUCTION TO TV SERVICING, 
by H. S. Swaluw and J. Van der Woerd. 
Philips Technical Library, 5% x 8 
inches, 266 pages. Distributed in U. S. 
by Elsevier Press Inc., 2330 Holcombe 
Blvd., Houston 25, Tex. $5.50 

For the radio technician who wants 
to learn television, this book describes 
European receivers with the 625-line 
picture system, but the same principles 
and service technique hold for our own 
system. Receivers are clearly described 
and illustrated and the theory is easy 
to understand. 

The author emphasizes service pro- 
cedure especially as applied to repairs 
in the customer's home. There are chap- 
ters on troubleshooting, test instru- 
ments suitable for home service, point- 
to-point measurement, etc. The author 
notes that most repairs do not require 
removing the chassis from the cabinet 
to the shop. 

Two modern receivers are analyzed 
from front end to power supply, circuit 
by circuit. Schematics are printed on 
loose sheets of high-grade paper, folded 
into a pocket in the cover for convenient 
reference. 

Approximately 100 pages are devoted 
to troubleshooting. Each listed defect 
occupies two pages. The left-hand page 
shows the result on a test pattern, while 
the right page shows how it looks on a 
cross-hatch generator. Pictorial effects, 
description and remedies are noted 
I without page turning, greatly simplify- 
| ing analysis. — IQ 



(Continued) 

R/C BIBLIOGRAPHY, by Paul F. 
Runge, Ace Radio Control, Higginsville, 
Mo. SVj x 8 ! /2 inch looseleaf, 18 pages 
plus 20-page catalog. $1 

An alphabetically arranged compre- 
hensive bibliography of the most per- 
tinent articles on radio control of 
models published between September, 
1950, and July, 1955, in 10 of the lead- 
ing model, hobby and radio magazines. 
Divided into sections on boats, planes, 
transmitters, control units and the like. 

With the rapid growth of radio con- 
trol, this bibliography should be a val- 
uable asset to hobbyists. 



SPECIALIZED HI-FI AM-FM TUNER 
MANUAL (Vol. 1), by John F. Rider 
Laboratory Staff. John F. Rider Pub- 
lisher, New York. 208 pages. $3.50 

A compilation of manufacturers' 
original specifications, circuit diagrams, 
photographs and troubleshooting and 
alignment data on AM, FM and AM- 
FM radios and tuners produced in 1950 
through 1955 by 22 manufacturers. 

RADIO AMATEUR QUESTION AND 
ANSWER LICENSE GUIDE (2d Edi- 
tion), by Martin Schwartz. American 
Electronics Co., New York, 32 pages. 
50c 

A guide and aid in preparing for 
Novice, Technician, Conditional and 
General radio amateurs' license exam- 
inations. There are over 200 questions 
and answers — mostly multiple-choice 
type — similar in content and construc- 
tion to those used by the FCC. One 
section is devoted to questions for 
prospective Novices and the other for 
would-be General, Conditional and 
Technician licenses. 



REPAIRING RECORD CHANGERS, 
by E. Eugene Ecklund. McGraw-Hill 
Book Co., New York. 271 pages. $5.95 

A practical manual on repairing 
record changers with a chapter on the 
mechanical aspects of magnetic tape 
recorders, it discusses in well-illustrated 
detail the operation of the various 
popular record changers and describes 
how defects are corrected. end 

CORRECTIONS 

There is an error in the 23rd line, 
second column, of the April editorial 
(page 33). Temperatures of hydrogen 
in the liquid and solid states should be 
Celsius (Centigrade) rather than Fahr- 
enheit: -253° C and -260° C. 

Our thanks to Chesley H. Johnson, 
of Massapequa, N. Y., for calling our 
attention to this error. 



There is a discrepancy in the "Im- 
proved CRT Tester" diagram on page 
171 of the January issue. The lead from 
the arm of S2's left-hand section should 
connect to the junction of the meter's 
positive terminal and the 500-ohm 
resistor, not the junction of the resistor 
and rejuvenate contact Si. 

This revision uses the 500-ohm re- 
sistor to limit cathode current as before. 
When wired as shown, the C-R tube is 
apt to be damaged when SI is thrown 

to REJUVENATE. 



150 



RADIO-ELECTRONICS 



www.americanradiohistorv.com 



School 
Directory 



LEARN TV 



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as service technician. Graduates in great demand; 
jobs are plentiful in this growing field. Other elec- 
tronic courses in radio operation and maintenance. 
Day or evening classes. Opportunity for employment 
in local industry. Approved for Korean veterans. 
Write for Catalog 111 Today 

INDIANAPOLIS ELECTRONIC SCHOOL 

312 E. Washington, Indianapolis 4, Indiana 



TELEVISION 



PREPARE FOR A GOOD JOB! 

BROADCAST ENGINEER 
ELECTRONICS 
RADIO SERVICING 



Television Servicing 



(Approved for Veterans) 
SEND FOR FREE LITERATURE 
BALTIMORE TECHNICAL INSTITUTE 

1425 ELTAW PLA* E. ItALTIMOltE 17, MD. 



A -,5?slllDIIIC 




Be a "key" man. Learn how to send and 
receive messages in code by telegraph 
and radio. Commerce needs thousands of 
men for Jobs. Good pay. adventure, in* 
terestlnc work. Learn at borne quickly 
through famous Candler System. Qual- 
ify for Amateur or Commercial Li- 
cense. Write for FREE BOOK. 

CANDLER SYSTEM CO. 
DePt.3-E.Box928.Denveri.Colo..U.S.A. 



if GET INTO 

ELECTRONICS 

You can enter this uncrowded. Inter 
esting field. Defense expansion, new 
developments demand trained special 
ists. Study al) phases radio & elec- 
tronics theory and practice; TV; KM; 
broadcasting; .servicing; aviation, nia- 
line, police radio. 18-month course. 
Graduates in demand by major com- 
panies. U.S. or equivalent required, 
liegin January. March. June. Septem- 
ber. Campus life. Write for catalog. 
VALPARAISO TECHNICAL INSTITUTE 

Dept. C Valparaiso. Indiana 



ELECTRON I C S 




ENGINEERING DEGREE 

IN 27 MONTHS 




Prepare for un- 
limited oppor- 
tunities in elec- 
tronics! H.R. de- 
gree in 27 months. Intensive, specialized courses. Math, 
electrical engineering, TV. advanced radio theory & de- 
sign. Mod. labs. Low tuition. Self-help. Also Aeronautical. 
Chemical. Civil. Electrical. Mechanical Engineering. G.I. 
approved. Enter June. Sept.. Dec. Mar. Catalog. 

INDIANA TECHNICAL COLLEGE 

1556 E. Washington Blvd., Fort Wayne 2, Ind. 



MAY, 1956 



SSJ™ F.C.C. LICENSE ^ 

Guaranteed preparation, in a MINIMUM OF TIME, tor 
F.C.C. commercial operator examinations. Our highly 
specialized training is available by correspondence, or 
in resident classes in 

WASHINGTON, D.C. and HOLLYWOOD, CALIF. 

Write for our free booklet with complete details. 

GRANTHAM School of Electronics 

Desk 4-C, 821 19th Street N.W., Washington 6. D.C 



RADAR 



Our school is now introducing a correspond- 
ence course in Radar, Microwaves, and 
Loran. Get your FCC endorsement, high 
paying job in industry as a radar technician. 
Special introductory offer. Write 

PROGRESSIVE ELECTRONICS INSTITUTE 
P.O. Box 27764 Los Angeles 27, Calif. 



BARN MOM MONey- 
BE A PROFESSIONAL 



TELEVISION 

SERVICE 
TECHNICIAN 



GET DOWN-TO-EARTH 
PRACTICAL TV TRAINING 
WITH WTI EXPERTS FOR 
THE TOP PAYING $5,000- 
StO.000 PER YEAR JOBS. 

UHF — COLOR — VHF 

Master the latest, up-to- 
the-minute TV and Color 
TV developments QUICKLY. 
WESTERN TV offers real experience on live equipment 
in our BIG SHOPS AND LABORATORIES in the shortest 
practical time under expert Instructors. Graduates are 
in big demand because they have the "field expe- 
rience" necessary for immediate "bench" or super* 
visory positions. You learn every phase of Radio and 
TV servicing (AM, FM, VHF, UHF). WTI men win fast 
promotion ... can demand better pay ... develop 
highly profitable businesses of their own with the 
latest and most PRACTICAL PERSONALIZED TRAINING 
BEHIND THEM. You concentrate all your time on being 
a PROFESSIONAL TV SERVICE TECHNICIAN — non- 
essential math and engineering theory omitted, YOU 
CAN EARN WHILE YOU LEARN. Special Finance Plan. 
APPROVED FOR VETERANS. Find out how you can get 
into the TOP PAY GROUP — Send for this fact-packed 
book NOW! 

WESTERN America's Leading 

TELEVISION m Television 
I N STITUTE Servicing School 



Western Television Institute Dept. E-556 
| 341 W. 18th St., Los Angeles 15, Calif. 

Without obligation, please send FREE fully Illustrated | 
J booklet. (NO salesman will call.) 

| NAME \ 

! ADDRESS 





_Z0NE STATE 



Your choice of school 
is highly important 
to your career in 

i INDUSTRIAL 
flJl^jf ELECTRONICS 



RADIO 



TELEVISION 



Become an 

ELECTRICAL 
ENGINEER 

or an 

ENGINEERING 
TECHNICIAN 

at 

in Milwaukee 

Choose from courses in: 

ELECTRICAL ENGINEERING 

Bachelor of Science degree in 36 to < 2 
months with a major in electronics or 
electrical power. 

ELECTRICAL TECHNOLOGY 

Engineering Technician certificate 
in 12 months in electronics, radio, or 
electrical power; 

Associate in Applied Science degree 
in 18 months in radio and television. 

TECHNICAL SERVICE 

Service certificate in 6 months in electric- 
ity; in 12 months in radio and television. 

MSOE — located in Milwaukee, 
one of America's largest indus- 
trial centers — is a national 
leader in electronics instruction 
— with complete facilities, 
including the latest laboratory 
equipment, visual aid theater, 
amateur radio transmitter — 
offers 93 subjects in electrical 
engineering, electronics, radio, 
television, electrical power, 
and electricity. 

Advisory committee of lead- 
ing industrialists. Courses 
approved for veterans. Over 
50,000 former students. 
Excellent placement record 



TERMS OPEN JULY. SEPT EM- 
BER. JANUARY. APRIL 

Choose wisely — your 
future depends on it. Write 
for more information today i 



MILWAUKEE 

SCHOOL OF ENGINEERING 
Dept. RE-556. 1025 N. Milwaukee Si. 

Milwaukee 1, Wisconsin 

Send FREE career booklets on: 
□ Electrical Engineering □ Radio-Television 

I am interested in. - — 

(Name of course) 

Name Age..—. 

Address 

City Zone State. — „ _ 

If veteran, give discharge dateu. — 



151 



www.americanradiohistorv.com 



^Only the 5 TOP QUALITY brands of"^ 

STANDARD 
BRAND TUBES 

AT SENSIBLE PRICES! 

• Individually boxed • First quality only 
• Brand New • Standard RTMA guarantee 

• No private brands •No rejects 

• No rebrands or rewashed bargains 



Free' Newest handy air 
■ ■ %f\im or{ iering convert 
popular rcplacerr 



lil order form for your 
ce Lists Over 400 
types. 



WRITE FOR YOUR FREE COPY TODAY! 

» Lists ALL popular TV & radio types. 

• Makes mail-ordering a real pleasure. 

• All tube orders over 525 OO (with remittance) 
postpaid. 



SPECIAL-PURPOSE TUBES 

Write for our complete listing on Transmitting, Indus- 
trial, Special-Purpose Tubes, and Crystal Diodes. Wc 
STOCK over lOOO types at excellent prices. 



TRANSMITTING TUBE SPECIALS 

4PR60A SSO.OO | 7SOTL $40.00 

304TH 8.75 803 2.00 

307A „. .80 | 807W, 5933 2.85 

4S0TH 47.50 1 872A 1.25 



EQUIPMENT SPECIALS 



New & used at bargain prices. Subject to prior 
All items guaranteed to be as advertised. 
LM-1S NAVY FREQ. METER W/orig. book, 

xtal & pow. supply L.N 1! 

KAY MEG A -MARKER SR.. 13 channel xtal 

freq. TV marker, vy gd 

SNOOPERSCOPE TUBES CRI-143 cr 147. New 

INFRA-RED FILTER for above. New 

<frce data supplied with cither above) 
115 V. SELENIUM RECTIFIER, l/ 2 amp. full 

wave bridge type, Sarkes-Tarzian. New 
SELSYN MOTORS, 115 volt, 60 cycle, each ..... 



49.50 
3.50 
1.50 



2 COLOR TUBE CARTONS 



Keeps your tube stock neat. New 
safety partition prevents tube 
breakage. Distinctively lithograph, 
ed in glossy red and black. The 
most distinctive tube carton avail* 
able today. Minimum quantity: 100 
of any one size. Write for case tot 
prices. 

SIZE FOR TUBE PER 100 

mature 6AU6, etc $1.00 

GT GSN7, etc 1.25 

Large GT 1B3. etc l.SO 

Large G 5U4G. etc 2.00 

WHITE GLOSSY BOXES 
Completely blank. No printing or 
color, otherwise same as above. 
Tie high quality, same low 
ces. Specify "WHITE" when or- 
dering. 

TUBE STACKERS 
White glossy only. Ministacker 
holds 10 Mini, tube cartons: "GT" 
stacker holds 10 "GT" cartons. 
SIZE PER 100 

Ministacker Sl.SO 

GT 2.00 




SMALL PARTS BOXES 

Craft colored folding cardboard boxes ideal for kits of 
small parts, storage of seldom used material, light 
shippinrj. and a million and one other uses around the 
shop. Quantity is limited so order now! Available in 
two sizes. 

" x 4" X 5" 1 C EITHER SIZE 

" x 6" x 5" ea. (in case lots of 200 boxes) 

Single boxes lVstc ea. 



DIRECTRON SELENIUM RECTIFIERS 

Full Wave Bridge Type 



Max. 
Amps. 


18VAC 
14VDC 


36 VAC 
28 VDC 


54 VAC 
42 VDC 


72 VAC 
56 VDC 


130 VAC 
100 VDC 


1 


SI. 35 


$2.30 


$3.70 


$4.50 


$7.40 


2 


2.00 


2.75 


5.30 


5.90 


9.15 


2*2/3 


2.90 


4.10 


5.75 


7.85 


12.70 


4 


3. SO 


6.40 


11.25 


14.35 


21.70 


6 


3.95 


7.70 


12.75 


17. 30 


29.65 


IO 


5.85 


11.35 


19.40 


24.80 


41 .25 


12 


7.20 


14.25 


22.00 


2i,./5 


43.85 


20 


13.05 


25.05 


37 25 


48.75 


78.50 


24 


14.25 


28.75 


44.50 


57.65 


81 .00 


Complete line of new rectifier transformers 


, chokes 



nd filter capacitors In stock at all times 
ordered at same time as selenium rectifiers 
nediate delivery. Write for complete pri< 
We build other Selenium Rectifiers 
Transformers and Chokes to your specific 



FILAMENT TRANSFORMER SPECIALS 

Super Electric #2Z9600.12 

Sec. 5 VCT @ 3 A; 5 VCT @ 3 A: 5 VCT @ 6 A. 
Pri, 220 volts. 60 cycles. Special Each $3.95 



Kenyon #S-10694 

Pri. 210-220-230-240 volts, 60 cy. 
Scc. 5 VCT @ 10 A. Special Each....... , 



Collins "672-1141 00 

Pri 210-220-230-240-250 volts. 60 cy. 
Sec. 2.5 VCT @ 15 A. Special Each 



WRITE FOR "BARRY'S GREEN SHEET' 
ISSUED MONTHLY. FREE! 



TERMS: 2SO/„ deposit with order, balance C.O.D. 
AM merchandise guaranteed. F.O.B. N.Y.C. 



Barry ,u sb." 



ICS 



512 Broadway, Dept. RE, N.Y. 12, N.Y. 

Call Us Day or Night 
24-Hour Phone Service 

,Phorte: WAIker 5-7000 t 



ADVERTISING INDEX 



RADIO-ELECTRONICS d oes not assume responsibility for any errors appearing in the 
below. 



index 



Aerovox Co 118 

Alliance Manufacturing Co . 115 

Allied Radio Corp ..17, 85 

American Phenolic Corp 92 

Arkay Radio Kits, Inc 136 

Astron Corp 10 

Atlas Sound Corp 127 

Audel Publishers — ., 4 133 

B & K Manufacturing Co 107 

Barjay Co 148 

Barry Electronics 152 

Bell Telephone Labs. . 30 

Benco Television Associates Ltd 144 

Bendix Radio 138 

Brooks Radio & Television Corp 128 

Cabinart =. 127 

Cannon Electric Co 124 

Capitol Radio Engineering Institute 23 

CBS-Hytron 26 

Channel Master Corp... 13 

Chicago Standard Transformer 

Corp 101, 139 

Clarostat Manufacturing Co 81 

Cleveland Institute of Radio 

Electronics 11 

Columbia Wire & Supply Co ..125 

Cornell-Dubilier Electric 

Corp 28, 100, 129 

Coyne Electrical & Television 

School 124, 138, 147 

Delta Distributing.... 142 

DeRo Electronics ..133 

DeVry Technical Institute ...7, 19 

Dressner 139 

DuMont (Allen B.) 

Labs. Inside Front Cover 

EBY Sales Co. ....149 

Editions Radio .....101 

Editors & Engineers 130 

Electro Products Labs .142 

Electro-Voice, Inc Inside Back Cover 

Electronic Instruments Co. 

(EICO) 31 32 

Electronic Measurement Corp .116 

Electronic Publishing Co., Inc.... .106 

Elgin National Watch Co. 

(Electronics Div.) 131 

Erie Resistor Corp 136 

E-Z Way Towers, Inc 126 

Federal Telephone & Radio..... 25 

Futuramic 118 

General Cement Manufacturing 

Co. 114, 126, 141 

General Industries Co 12 

Gernsback Library, Inc 141, 145 

Hallicrafters Co 137 

Heath Co 63-74 

Hi-Fi Fabrics Institute , .120 

Hudson Specialties Co 143 

Hughes Research & Development 

Labs 96 

Indiana Technical College 120 

Instructograph Co 101 

International Business Machines 154 

International Rectifier Corp 110 

Jensen Industries. 130 

Jerrold Electronics Corp 97 

Jones & Laughlin Steel Corp 119 

Karlson Associates, Inc 140 

Kedman Co... 96 

Kuhn Electronic Products 96 

LMB 120 

Lafayette Radio 153 

Lektron Specialties 132 

Mallory (P. R.) & Co.. 104, 105 

Merit Coil & Transformer Corp 8 



Miller (Gustave) 139 

Miller (J. W.) Co 124 

Mosley Electronics, Inc 110 

Moss Electronics Distributing 98-99 

National Radio Institute 3, 15 

National Schools 5 

North American Philips Co., Inc 20 

Opportunity Adlets 148 

ORRadio Industries 133 

Perma-Power Co 96 

Pernio, Inc 84 

Phaostron Instrument & Electronic 

Co 18 

Philco Corp 108-109 

Pickering & Co.. 16 

Precise Development Corp 113 

Precision Apparatus Co 103 

Precision Electronics 142 

Progressive Edu-Kits, Inc. 112 

Quality Electronics 146 

Quam-Nichols 102 

Quietrole Co 132 

Radiart 28 

RCA Components Division 121 

RCA Institute, Inc 29 

RCA Service Co. 78 

RCA Tube Division Back Cover 

Radio Television Training 

Association 21 

Ram Electronics Sales 143 

Raytheon Manufacturing Co 9 

Remington-Rand Univac 22 

Research Inventions & Manu- 
facturing Co 138 

Rider (John F.), Inc 27 

Rinehart Books, Inc.. 80, 126 

Rohn Manufacturing Co 77 

Ronette Acoustical Corp 136 

Sams (Howard W.) & Co., Inc 14, 93 

Sangamo Electric Co 6 24 

Service Instrument Co 132 

Simpson Electric Co, 87 

South River Metal Products Co 120 

Sprague Praducts Co 139, 144, 146 

Stan-Burn Radio & Electronics 134 

Standard Coil Products Co., Inc 89 

Stanley Electronics Corp... 149 

Supreme Publications 135 

"TAB" 139 

Technical Materiel Corp 127 

Telco Electronic Mfg. Co ....126 

Teleparts Co 139 

Television Hardware Mfg. Co 141 

Tenna Manufacturing Co 88 

Terado Co. 130 

Thompson Products Co 95 

Triad Transformer Corp 106 

Tube Mart 140 

Tung-Sol Electric Co 6 

University Loudspeakers Ill 

Vokar Corp ,...131 

Weston Electrical Instrument 

Co 122-123 

Winegard Co 117 

Xcelite Inc, 146 

SCHOOL DIRECTORY PAGE 150-151 

Baltimore Technical Institute 
Candler System Co. 
Central Technical Institute 
Grantham School 
Indiana Technical College 
Indianapolis Electronic School 
Milwaukee School of Engineering 
Progressive Electronics Institute 
RCA Institutes. Inc. 
Tri-State College 
Valparaiso Technical Institute 
V.S.I. Television School 
Western Television Institute 



152 



RADIO-ELECTRONICS 



www.americanradiohistorv.com 




132 PAGE ELECTRONIC 
CATALOG 

Packed with the largest selection of Electronic, Radio ond 
T.V Ports, and equipment. PA, Hi-Fi systems, tubes, on- 
ternas. Transistor Kits, parts and components, Test Equip- 
ment, new build your own kits, tools, books. Microscope, 
drafting equiprrent. Binoculars, Telescopes, All Radio, TV 
and Horn supplies - ALL AT GREAT SAVINGS - For the 
ecanomy minded servicemen, dealer, engineer and tech- 
nician. CHUCK FULL OF BUYS! SEND FOR YOUR FREE 
COPY TO-OAY. 




Tust a f£w of Lafayette's Values 

■ 



2 TRANSISTOR POCKET RADIO KIT 




Packed into a 2 Vfc "x3»/2"x 1 Vi " Plastic case 
This Two Transistor" pius crystal diode radio 
kit offers many surprises, utilizing a regener- 
ative detector circuit with transformer coupled 
audio stage, gives you high gain and excel- 
lent selectivity. Pulls in distant stations witu 
ease with more than ample earphone volume. 
Kit comes complete with two transistors, 
crystal diode, loopstick. Artronne transistor 
audio transformer, resistors, con.lensers. plas-. 
tic case. etc. Including schematic and In-, 
structlons. 

KT-68A Complete Kit less earphones. 

Net 11. SO 

MS-260 New Super Power Dynamic 

Earphone, ideal for Transistor 

Circuit imp. 8000 ohm, D.C. 

2000 ohm 3-93 



HIGH SENSITIVITY 20,000 OHM PER VOLT DC 
10,000 OHM PER VOLT AC MULTITESTER 

3S ua 3" METE* SILVER CONTACT SELECTOR SWITCH 1 % PRECISION RESISTOR 



LOOK AT THESE FULL SCALE RANGES! 

D.C, VOLTS: 0-6; 0-30; 0-120; 0-600; 0-1200; 0-6000 Volts— A. C. 
VOLTS; 0*6; 0-30; 0-120; 0-600; 0-1200 Volts— RESISTANCE: 0-10K; 
0-100K; 0-1 Meg; 0-10 Megohms — D.C. CURRENT: 0-60 Mlcroamp, 
0-6; 0*60; 0-600 Mill lamps — DECIBEL: —20 to +17 db (0 db - 
0.774V)— CAPACITY: .0001 - .01; ,00S - .15 mfd— INDUCTANCE: 20- 
2000 millihenry— OUTPUT RANGES: 0-6; 0-30; 0-120; 0-600; 
0-1200 Volts 



HIGH-FIDELITY TURNOVER CARTRIDGE 



The new Lafayette high sensitivity Multlterfer is a complete instrument (not a kit). In addition to Its unusual 
Sensitivity of '20.000 OHMS PER VOLT ON D.C. AND 10.000 OHMS PEK VOLT ON A.C.. and the extraordi- 
nary number and scope of Its ranges, it bs packed with features that would make it cost at least twice a*, 
much If made in this country. Uses 1 % precision resistors, silver contacts on selector switch, 35 ua 3 ' 
meter Size: 6V4" x 4Y4" x 2V2". Complete with batteries and leads. Shipping weight 41/2 lbs. 

RW-30A - Singly. Each 19.95 

In lots of 3. each 19.25 




lef . Prkt 



40-14000 CYCLE 

NEVER BEFORE AT SUCH A PRICEI 

Lafayette brings you one of the fin- 
« est high-fidelity turno\er cartridges^ 
AT AN UNBELIEVABLE PRICE! 
Frequency response from 40-14000 
cycles + 2 db. Has 2 sapphire styli 
to play all speeds. Needle pressure 
only 5 grams on LP cond 12-15 
grams on 7 8. Output is .5 volts. 
Complete with turnover mechanism 
and knob, fits Webster, Garrad, VM, 
Collaro and tone arms of leading 
manufacturers of record changers 
and players. 

PK-79 Singly, Each 2.7S 

In lots of 3, Each 2. SO 



TRANSISTOR CHECKER KIT 



• Checks Shorts/ Leakage/ and Gain 

A "must" for servicemen, experimenters and 
engineers. Tests both PNP and NPN type 
transistors. Gives 2 separate checks: first 
GOOD-BAD check for shorts and leakage, and 
second for GAIN. Gray hammertone case 5 V4 ' 
x 3" x 2V4". Kit includes case, meter, all 
part* with full assembly and operating instruc- 
tions. Simple to build. Fast, accurate. Shpg» 
wt. 3 lbs. 

KT-86 Kit 7.93 



NEW POCKET AC OC VOM MULTITESTER 
2,000 ohm per Volt on AC & DC 



• Completely wired — Not a kit 

Accurate VOM with a sensitivity of 2000 
ohms per volt on both AC and DC. Single se- 
lector switch. 3" 160 amp. meter. Scales: 
DC Volts: 0-10-50-500-1000; AC Volts: 
0-10-50-500-1000; Ohms: 0-10K, 0-1 Meg; 
DC Current: 500 iia and 500 ma; Decibel: 
— 20 to +22, +20 to 36; Capacity: 250 mmf 
to .2 mfd and .005 to 1 mfd. Heavy plastic 
panel, metal bottom. 4V4" x 3V 2 " x ltya"- 
With batteries and test leads. Shpg. wt. 4 lbs. 
RW-27A - 7.95 



NEW! ALL-PURPOSE 
DYNAMIC EARPHONE 



FOR RADIO AND TV LISTENING 
FOR SUBMINI ATURE, MINIATURE 
AND TRANSISTOR RECEIVERS 

I A sensitive all-purpose earphone designed 
for your listening pleasure. Combines the 
I range of a dynamic earphone with the per- 
I formance of its special magnet to give you 
I excellent reproduction. Lightweight and 
I equipped with ear support that slips com- 
I fortably over your ear. You can relax! The 
I support is practically invisible — the ear- 
I phone can't slip out — it can't fall off. 
I Ideal for use with TV and radio sets, am- 
plifiers, miniature and transistor receivers etc. Complete with 
3 ft cord. A super value for the price! 
MS-278 — 3000 ohm impedance, 1000 ohm DC resist- 
ance, with phone tip plugs ....Net 1.95 

MS^277 — 6 ohm impedance, with phone tip plugs. For 

Silent Radio and TV Listening or Viewing Net 1.95 
MS-273 — 3000 ohm impedance, 1000 ohm D.C resist- 
ance, with subminiature phone plug and 

matching phone jack Net 2.39 

MS-279 — 6 ohm impedance, with subminiature phone 
plug and matching phone jack. For Silent 
Radio and TV Listening or Viewing Net 2.39 





NEW! EXCLUSIVE — REVOLUTIONARY DESIGN! 

TRANSISTOR 2 GANG VARIABLE SUPER-HET CONDENSER — 
THE SMALLEST SUPER-HET VARIABLE CONDENSER IN THE WORLD! 



Lafayette does it again with this new super 2 gang midget variable con- 
denser. An exciting and proven innovation in the transistor parts field! 
Manufactured for top performance in transistor super-het circuitry, it 
measures onlv V2 " x 1" x 1", Has 2 gangs specifically designed for 
transistor suner-hets — 10 to 2 08 mmf capacitance on the antenna section, 
and 10 to 100 mmf on the cut oscillator section. Self contained trimmers. 
Tunes through 180°. Entirely enclosed in a transparent plastic case! The 
smallest complete 2 gang variable for super-hets in the world! Offers un- 
limited possibilities to the experimenter. 

MS-270 Net 1.95 



MATCHED 
COIL SET 



MS-2G5- Osc. 
MS-272-Ant. 



Coil 
Coil 



Net .79 Ea. 
Net .95 Ea. 



365 MMF SINGLE GANG SUPER MIDGET VARIABLE CONDENSER 



For exceptional performance in TRF and experimental transistor and sub- 
miniature circuitry. 1 0 to 365 mmf single gang. Enclosed in transparent 
plastic case. ^2" x 1" x 1". 

MS-274 Net 1.25 



AN ENTIRE SYMPHONY ON ONE REEL OF TAPE! 
NO MORE ANNOYING INTERRUPTIONS! 

Lafayette did it again! New plastic base. TIME + Vz 
High Fidelity Recording Tape at an amazingly low 
price! Over 1 V2 hrs. of playing time on a single reel 
at 71/2" per second on dual track recording. At 3 av' 
per second you get 3 hours and 12 minutes. The same 
quality that has made the Lafayette Standard Tape the 
nation's outstanding value. 40-1 5, 0O0 cycle response 
at 7 V*" per second assures you of the finest profession- 
al quality high fidelity recordings. A true Lafayette 
value hacked up with our Money Back Guarantee. You 
be the judge — try Itl 



LAFAYETTE TIME + Va TAPE 
1800 FT. -7 INCH REEL 



) Lots of 10, 
I Eat 
\ Singly. Eac 



Each $2 45 
Each $2. 59 




CRYSTAL MICROPHONE 



COMPARE IT WITH ANY MIKE 
AT 2 to 3 TIMES THE PRICE 

A quality crystal Microphone for 
PA systems, house recorders, etc. 
Frequency response 30 to 10.00O 
cycles. Output level — 52 db. Pro- 
vides ample output for use with 
low gain amplifiers. Complete with 
3 ft. of shielded cable. ShPg. wt.. 
3Va" lbs. 

PA-24— in lots of S^ach 3.95 
singly, each ........ 4.2S 




f&t $ QndiO »MNX.N.T.|S tfL-fflrftiHiW 
' { { r /Y^ NCwARMi 24Ceotr>l*<e 

100 SIXTH AVE. PLAlNHtLD.H j W9 WeslZflflSt, 

NEW YORK, N.Y. bostonmass .'no Federal St. 

Include poitoge with order. 



BUILD YOUR OWN 
TRANSISTOR 



COMPLETE 8 PAGE 
BROCHURE 



REMOTE CONTROL 
FOR SILENT 
TV VIEWING 




Send FREE 132 Page 

Lafayette Catalog 



For Hord«of* Heorino. 

• For Lote Littenin? 

One or two people can both 6ee or bear 
the program with the loud speaker cut off. 
The hard-of-hearlng can listen to radl or 
TV without turning the volume so high 
that others can't stand the noise. Comes 
completo with miniature phone and 20 ft. 
of cable. Shpg. wt. 3 lbs. . 
MS-123 ...Net O.50 



| City 



MAY, 1956 



www.americanradiohistorv.com 



153 



IN RETURN 

FOR 
CHARACTER 
...A CAREER 



Because the finest single attribute anyone can offer 
is character, this, basically, is what IBM asks of its 
people, whatever their special aptitudes or abilities. 
IBM offers them in return -not just a job -but a 
career. 

IBM electronic field technicians, for instance, re- 
ceive more than training and early responsibility; 
they have a chance to work with the world's largest 
computer, use the latest testing equipment, employ 



the finest computer testing techniques yet devised. 
Above all, they have the satisfaction of joining the 
electronics industry's most advanced program, des- 
tined for long-range national importance. 

You could ask for no finer future. 

// you are beticeen 19 and 32 and have at least a 2-year 
technical school background, with emphasis on electronics, 
you can do important work on COMPUTER INPUT- 
OUTPUT functions. Write: Nelson O. Beyer, IBM, Room 
3105, Neighborhood Rd., Kingston, N Y, 




i 

4 



The 702 Electronic Data Processing Machine, typical of advances that have made 
engineering work at IBM one of the most provocative experiences in electronics. 

INTERNATIONAL BUSINESS MACHINES CORPORATION 



IBM 


Producer of electronic data 
processing machines, 
electric typewriters, and 
electronic time equipment. 


(D 





154 



RADIO-ELECTRONICS 



www.americanradiohistorv.com 



STOP UNWANTED SOUNDS 





AI the advantages of the E-V Variable D* are now available in the new 
high-fkfclit> 664".., for public address, recording, communications and similar 
applica ion.*. Uniform cardioid polar pattern provides h gh front-to-back discrimination 
agunst unwanted sounds, without close-talking boominess. Easily solves sound 
pidc-up anc reproduction problems under a great variety of conditions. Gives distinct, 
natural repioiuction of voice and music. Increases wor<ing distance from 
microphone. Gives greater protection against feedback Especially useful where 

ambient noise and severe reverberatioci ^xJ 5 t. Pop-proof filter minimizes 
wind and breath blasts. E-V Acoustal oy d aphragm guarantees 
smooth wide-range reproduction. Can be used on a floor or desk stand 
or carried in the hand. No finer microphone for performance 
and value! Write for Technical Speeifieituir Sheet W65. 

•EV Pat. Pend. 

Model 664. Variable D* S jper-Cardioid Dynamic Microphone. 
Unfform response at a I f eciencies from 60 to 13,000 cps. Output 
level —55 db. 150 ohm and Hgh impedance. Impedance changed by 
mo zing one connection ir connector. Line balanced to ground and 
phased. Acoustalloy diaphragm, shielded from dust and magnetic 
particles. Alnico V and Ar~rco magnetic iron in non-welded cir- 
cui . Swivel permits airring directly at sound source for most 
effective pick-up. Pressure :«st case. %"— 27 thread. Satin chrome 
finish. 18 ft. cable wrh MD4M connector. On-Off switch. Size: 
1% in. diam. 7 3 /i6 in. long n«" including stud. Net wt.: 1 lb. 10 oz. 

List Price $79.50 

Model 419 Desk Stand available for use with the "664" (extra). 





ft" 



ELECTRO-VOICE, RNC. • BUCHANAN, MICH. 

Export: 13 East 40th Street, New York 16, N, Y. U. S.A. Cables; Arlab 



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